WWEESSTT VVIIRRGGIINNIIAA … · West Virginia Voluntary Remediation and Redevelopment Act Guidance...
Transcript of WWEESSTT VVIIRRGGIINNIIAA … · West Virginia Voluntary Remediation and Redevelopment Act Guidance...
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VERSION 2.1
WVDEP Mission Statement
“Use all available resources to protect and restore West Virginia’s environment in concert with
the needs of present and future generations.”
West Virginia Voluntary Remediation and Redevelopment Act Guidance Manual
DISCLAIMER
This document is intended as guidance only. The procedures and information
contained herein are intended to assist in implementing the Voluntary Remediation and
Redevelopment Act (“VRRA”), W. Va. Code §22-22-1 et seq., and the rules promulgated
pursuant thereto. This guidance document is not intended to and does not create any rights,
claims, causes of action, or remedies in addition to those afforded by VRRA, the rules
promulgated pursuant thereto, or other statutes, rules, or laws of West Virginia. This guidance
document is not intended to and does not replace or change any part or provision of VRRA or the
rules promulgated pursuant thereto.
This guidance document has been issued by the West Virginia Division of Environmental
Protection (“DEP”), Office of Environmental Remediation (“OER”), for use by its staff, by the
regulated community, and by the citizens of this State. There is no intent on the part of the DEP
or OER to give this guidance the same weight or deference as a statute, rule, adjudication or rule
of law. This document provides a framework within which the DEP can exercise its
administrative discretion. The DEP specifically reserves the right to deviate from this guidance
document where circumstances may warrant such action.
West Virginia Voluntary Remediation and Redevelopment Act Guidance Manual
ACKNOWLEDGEMENTS
The Guidance Manual was written by the Technical Subcommittee of the Voluntary
Remediation and Redevelopment Act Steering Committee. The Division gratefully
acknowledges the work of the many persons who gave tirelessly of their time, energy and
expertise.
Technical Subcommittee Members:
Mary Anderson, League of Women Voters
Jim Bodamer, WV Manufacturers Association, Chair
Ann Bradley, WV Chamber of Commerce
Marguerite Carpenter, WV Manufacturers Association
Ken Ellison, Division of Environmental Protection
Jim Kotcon, West Virginia University
Ron Potesta, WV Association of Consulting Engineers
Rudy Schuller, WV Oil & Natural Gas Association
The Division also acknowledges the assistance and contributions of individuals
supporting the Technical Subcommittee:
Rachael Bell, WVU Graduate School
Jerome Cibrik, Union Carbide
David Hight, Division of Environmental Protection
William Jones, WVU Graduate School
Gale Lea, Jackson & Kelly
Mark Mummert, Environmental Consulting Inc.
Jan Taylor, National Institute for Chemical Studies
Mindy Yeager, Potesta & Associates
The Division wishes to acknowledge the National Institute for Chemical Studies for
coordinating the expert peer review. The following expert peer reviewers have provided
recommendations on the technical accuracy and completeness of the Guidance Manual, many of
which were incorporated into the final version.
Waste and Chemical Management Division, EPA Region III
Hazardous Site Cleanup Division, EPA Region III
Terrie Baranek, ECT.CON Inc.
William Brattin, ISSI, Incorporated
Nancy Doerrer, American Industrial Health Council
Bruce Fishman, RBR Consulting, Inc.
Glenn Suter, Oak Ridge National Laboratory
Additional thanks go to key DEP staff support.
Rhonda McGlothlin
Wilma Pomeroy
WEST VIRGINIA
VOLUNTARY REMEDIATION AND REDEVELOPMENT ACT
GUIDANCE MANUAL
Section 1.0 OVERVIEW OF THE VOLUNTARY REMEDIATION AND
REDEVELOPMENT PROGRAM 1 - 1
1.1 General Structure of the Program 1 – 3
1.1.1 Responsibilities of the Licensed Remediation
Specialist 1 – 3
1.1.2 Remediation Standards Concept 1 – 4
1.1.3 Flexible Use of Remediation Standards Options 1 – 4
1.1.4 Applicability of the VRRA to a Site 1 – 7
1.2 Sequence of Actions for Implementation of VRRA 1 – 7
1.2.1 Site Assessment 1 – 8
1.2.2 Submission of an Application for Voluntary
Remediation and Redevelopment of a Site 1 – 8
1.2.3 Public Notification and Involvement 1 – 10
1.2.4 Remediation Standard Selection 1 – 14
1.2.5 Development of Risk-Based Concentrations 1 – 14
1.2.6 Submittal of the Remedial Action Workplan 1 – 14
1.2.7 Remedy Implementation 1 – 15
1.2.8 Closure / Remediation Verification 1 – 15
1.2.9 Final Report Submitted for WVDEP Approval 1 – 15
1.2.10 WVDEP Issuance of Certificate of Completion 1 – 16
1.3 Interaction of the Voluntary Remediation Program With
Other Environmental Programs 1 – 18
1.4 References 1 – 19
Section 2.0 SITE ASSESSMENT 2 - 1
2.1 Site Characterization Objectives 2 – 1
2.2 Preliminary Characterization 2 – 3
2.2.1 Evaluation of Historical and Current Land Uses
to Identify COPCs 2 – 3
2.2.2 Preliminary Evaluation of Site Physical
Characteristics 2 – 4
2.2.3 Preliminary Identification of Potential Human
and Ecological Receptors 2 – 5
2.2.4 Develop a Conceptual Site Model 2 – 9
2.2.5 Risk Evaluation 2 – 11
2.3 Develop Data Requirements for Sampling and Analysis Plans 2 – 11
2.3.1 Risk Assessment Data Requirements 2 – 14
2.3.2 Data Requirements for Remedial Action Design
(if applicable) 2 – 15
2.3.3 Data Requirements for Modeling (if applicable) 2 – 16
2.4 Developing specific Investigation Techniques for SAPs 2 – 20
2.4.1 Data Quality Considerations 2 – 21
2.4.2 Selection of Analytical Methods 2 – 22
2.4.3 Health and Safety Considerations 2 – 23
2.4.4 Surface and Subsurface Soils 2 – 23
2.4.5 Storm Water Runoff 2 – 28
2.4.6 Site Infiltration and Vadose Zone Characteristics 2 – 30
2.4.7 Groundwater 2 – 30
2.4.8 Surface Water and Sediment Sampling 2 – 36
2.4.9 Indoor Air Quality (IAQ) 2 – 39
2.4.10 Tanks, Drums and Asbestos Containing
Materials (ACM) 2 – 41
2.4.11 Decontamination 2 – 44
2.4.12 Investigation Derived Waste 2 – 45
2.4.13 Modeling 2 – 52
2.5 Background Concentrations 2 – 58
2.5.1 Definition of Background 2 – 58
2.5.2 Comparison of Site Contaminant Concentrations
to Background 2 – 62
2.6 Contaminants of Concern 2 – 62
2.6.1 Field or Laboratory Contaminants 2 – 63
2.6.2 Low Concentrations and Low Frequency
of Detection 2 – 63
2.6.3 Unusually High Sample Quantitation Limits 2 – 64
2.6.4 Comparison to Background 2 – 65
2.6.5 Evaluate Essential Nutrients 2 – 65
2.6.6 Screen Against De Minimis or Benchmark Levels
to Identify COCs 2 – 65
2.6.7 Additional Issues for Consideration 2 – 65
2.7 Presentation of COCs in Tabular Format 2 – 67
2.8 References 2 – 67
2.8.1 Preliminary Characterization 2 – 67
2.8.2 Risk Assessment Data Requirements 2 – 67
2.8.3 Data Requirements for Remedial Action Design 2 – 68
2.8.4 Data Requirements for Modeling 2 – 68
2.8.5 Investigation Techniques for Sampling and
Analysis Plans 2 – 68
2.8.6 Background 2 – 72
2.8.7 Contaminants of Concern 2 – 73
Section 3.0 HUMAN HEALTH STANDARDS 3 – 1
3.1 Introduction 3 – 1
3.2 Human Health De Minimis Risk-Based Standard 3 – 3
3.2.1 De Minimis Standards for Soil 3 – 4
3.2.2 De Minimis Standards for Ground Water 3 – 4
3.2.3 Implementing the De Minimis Standards 3 – 5
3.3 Uniform Risk-Based Standard 3 – 5
3.3.1 Uniform Standards for Groundwater 3 – 6
3.3.2 Uniform Standards for Soil 3 – 7
3.3.3 Establishing the Uniform Standards 3 – 7
3.3.4 Uncertainty Analysis 3 – 8
3.3.5 Attaining Compliance with the Uniform Standard 3 – 8
3.4 Site-Specific Risk-Based Standard 3 – 10
3.4.1 Baseline Risk Assessment 3 – 10
3.4.2 Implementing Site-Specific Risk-Based Standards 3 – 23
3.5 References 3 – 25
Section 4.0 ECOLOGICAL RISK-BASED STANDARDS 4 – 1
4.1 De Minimis Ecological Screening Evaluation 4 – 6
4.1.1 Identifying Potential Receptors of Concern 4 – 7
4.1.2 Determination of Exposure Pathway 4 – 8
4.1.3 Exposure Characterization 4 – 9
4.1.4 Reporting Requirements 4 – 9
4.2 Uniform Ecological Evaluation 4 – 12
4.2.1 Benchmarks and Generic Exposure Models
for Uniform Ecological Evaluation 4 – 12
4.2.2 Applicant-Derived Benchmarks for Uniform
Uniform Ecological Evaluation 4 – 12
4.2.3 Risk Characterization Based on the Uniform
Ecological Evaluation 4 – 14
4.2.4 Reporting Requirements for the Uniform
Ecological Evaluation 4 – 18
4.3 Ecological Site-Specific Risk-Based Standards 4 – 18
4.3.1 Problem Formulation 4 – 19
4.3.2 Quantitative Exposure Analysis 4 – 20
4.3.3 Ecological Response Analysis 4 – 24
4.3.4 Risk Characterization 4 – 24
4.3.5 Remediation Standards Based on Ecological Risk 4 – 26
4.3.6 Uncertainty Analysis 4 – 26
4.3.7 Reporting Requirements 4 – 27
4.4 References 4 – 29
Section 5.0 RESIDUAL RISK ASSESSMENT 5 – 1
Section 6.0 PROBABILISTIC RISK ASSESSMENT 6 – 1
Section 7.0 REMEDY SELECTION AND EVALUATION 7 – 1
7.1 General 7 – 1
7.2 Identification of Candidate Remedies 7 – 2
7.3 Initial Screening of Candidate Remedies 7 – 2
7.3.1 Screening Criteria 7 – 4
7.3.2 Screening Method 7 – 4
7.4 Evaluation of Short-List Remedies 7 – 5
7.4.1 Evaluation Criteria 7 – 5
7.4.2 Evaluation Method 7 – 8
7.5 Inclusion of Natural Attenuation in Remedy Evaluation 7 – 9
7.5.1 Developing Evidence in Support of Natural
Attenuation 7 – 10
7.5.2 Simulation of Natural Attenuation 7 – 13
7.5.3 Conduct an Exposure-Pathway Analysis 7 – 14
7.5.4 Develop a Long-Term Monitoring Plan 7 – 15
7.6 References 7 – 15
7.6.1 Remedy Selection, Contaminant-Specific 7 – 15
7.6.2 Remedy Selection, Technology-Specific 7 – 16
7.6.3 Remedy Evaluation 7 – 17
7.6.4 Electronic Data Bases 7 – 18
7.6.5 Cost Analysis / Economics 7 – 18
7.6.6 Natural Attenuation 7 – 18
Section 8.0 REMEDIAL ACTION WORKPLAN 8 – 1
8.1 Purpose 8 – 1
8.2 Information Required 8 – 1
8.3 Remediation Standards 8 – 1
8.4 Remediation Measures 8 – 2
8.4.1 Selection of Alternatives 8 – 2
8.4.2 Natural Attenuation 8 – 2
8.4.3 Uncertainty or Risks 8 – 2
8.5 Remediation 8 – 3
8.6 Submittal 8 – 3
Section 9.0 FINAL REPORT 9 – 1
9.1 Contents 9 – 1
9.2 Appendices 9 – 1
9.3 Additional Documentation 9 – 1
9.4 Certification 9 – 2
Appendix A: Checklist For Conceptual Site Model Development
Appendix B: Determining Background Concentrations
Appendix C-1: Determination Of The Applicable Human Health Standard
Appendix C-2: Checklist To Determine The Applicable Ecological Standard
Appendix D: Equations For The Uniform Human Health Standards For Soil And
Drinking Water
Appendix E: Relative Absorption Factors And Bioavailability
Appendix F: Risk Assessment For Lead
Appendix G: References To Benchmark Screening Levels
Appendix H: Site Specific Risk Assessment
Appendix I: Probabilistic Methodologies In Risk Assessment
Appendix J: Office Of Water Resources In-Stream Monitoring Procedures To Determine
Impact On The Surface Water From Non-Point Source Site Remediation Projects
ACRONYM LIST
ACM Asbestos Containing Materials
ASTM American Society for Testing Materials
API American Petroleum Institute
ATSDR Agency for Toxic Substances and Disease Registry
BOD Biological Oxygen Demand
BTEX Benzene, Toluene, Ethylene, Xylene
CEPPO Chemical Emergency Preparedness and Prevention
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CERCLIS CERCLA List
CFR Code of Federal Regulations
CLP Contract Laboratory Program
COCs Chemicals of Concern
COD Chemical Oxygen Demand
COPCs Chemicals of Potential Concern
CSF Cancer Slope Factor
CSR Code of State Regulations
CWA Clean Water Act
DQOs Data Quality Objectives
Eh Redox Potential
EPCRA Emergency Planning and Community Right-to-Know Act
ERNS Emergency Response Notification System
FEMA Federal Emergency Management Agency
FISs Flood Insurance Studies
FSP Field Sampling Plan
GC-MS Gas Chromatography-Mass Spectrometry
GPA Groundwater Protection Act
HASP Health and Safety Plan
HAZWOPER Hazardous Waste Operations and Emergency Response
IAQ Indoor Air Quality
IDW Investigation Derived Waste
IDWMP IDW Management Plan
Koc Organic-Carbon Partition Coefficient
Kow Octanol-Water Partition Coefficient
LDRs Land Disposal Restrictions
LRS Licensed Remediation Specialist
MDL Method Detection Limit
MTBE Methyl Tertiary Butyl Ether
NAD North American Datum
NAPLs Non-Aqueous Phase Liquids
NESHAP National Emission Standards for Hazardous Air Pollutants
NIOSH National Institute for Occupational Safety and Health
NIST National Institute of Standards
NJDEP New Jersey Department of Environmental Protection
NPDES National Pollutant Discharge Elimination system
NPL National Priority List
NVLAP National Voluntary Laboratory Accreditation Program
NWWA National Water Works Association
OER Office of Environmental Remediation
OPPE Office of Policy, Planning and Evaluation
OSHA Occupational Safety and Health Administration
OSWER Office of Solid Waste and Emergency Response
OWM Office of Waste Management
PAHs Polyaromatic Hydrocarbons
PCBs Polychlorinated Biphenyls
PCE Tetrachloroethene
PCP Pentachlorophenol
PELs Permissible Exposure Limits
PIP Public Involvement Plan
POTN Publicly Owned Treatment Works
PPE Personal Protective Equipment
PQL Practical Quantitation Limit
QAPP Quality Assurance Project Plan
QA / QC Quality Assurance / Quality Control
RCRA Resource Conservation and Recovery Act
RfC Reference Concentration
Rfd Reference Dose
the Rule Voluntary Remediation and Redevelopment Rule (Title 60 Code of State Rules,
Series 3)
SAP Sampling and Analysis Plan
SCS Soil Conservation Service
SIC Standard Industrial Classification
SQL Sample Quantitation Limit
TCE Trichloroethene
TCLP Toxic Compound Leaching Procedure
TEGD Technical Enforcement Guidance Document
TICs Tentatively Identified Compounds
TNT Trinitrotoluene
TOC Total Organic Carbon
TPH Total Petroleum Hydrocarbons
TSCA Toxic Substances Control Act
TSD Treatment, Storage and Disposal
TSS Total Suspended Solids
TVOCs Total Volatile Organic Compounds
USDA United States Department of Agriculture
USEPA United States Environmental Protection Agency
USGS United States Geological Survey
UST Underground Storage Tank
UTM Universal Transverse Mercator
VRA Voluntary Remediation Agreement
VRRA Voluntary Remediation and Redevelopment Act
VOCs Volatile Organic Compounds
WHO World Health Organization
WV West Virginia
WVDEP West Virginia Division of Environmental Protection
WVDNR West Virginia Division of Natural Resources
XRF X-ray Fluorescence
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West Virginia
Voluntary Remediation and Redevelopment Act
Guidance Manual
1.0 OVERVIEW OF THE VOLUNTARY REMEDIATION AND REDEVELOPMENT
PROGRAM
The Voluntary Remediation and Redevelopment Act (VRRA) was enacted by the West
Virginia (WV) Legislature for the purpose of encouraging the voluntary clean-up of
contaminated sites and redevelopment of abandoned and under-utilized properties. Properties in
the state are not being productively used because of contamination or the perception of
contamination. Because many of these properties are located in areas with existing industrial
infrastructure, redevelopment of these sites can be less costly to society than developing pristine
sites.
The VRRA encourages voluntary remediation and redevelopment through an
administrative program set out in the WV Code of State Regulations, Title 60, Series 3 entitled
the Voluntary Remediation and Redevelopment Rule (the Rule), which became effective on July
1, 1997. The VRRA limits enforcement actions by the WV Division of Environmental
Protection (WVDEP), provides financial incentives to entice investment in brownfield sites, and
limits liability under environmental laws and rules for those who remediate sites under the
standards provided in the Rule.
Both the VRRA and the Rule were cooperatively developed by a diverse group of
stakeholders. This process has led to a strong program that is protective of communities and the
environment while promoting economic development in West Virginia. The VRRA provides for
flexibility in the voluntary clean-up of under-utilized properties and marks a turning point in
state environmental policy. Figure 1-1 depicts the process to be followed in the Voluntary
Remediation Program. Details of the process are provided in this section.
This Guidance Manual is provided to assist those who would like to participate in West
Virginia’s Voluntary Remediation Program. The information provided in this document is,
indeed, guidance. Although based on the VRRA and the Rule, this document does not carry the
weight of law or regulation. The following information is intended to provide guidelines and to
help lead an applicant through the Voluntary Remediation Program. Technical and scientific
methods included with this guidance are acceptable to the WVDEP but are, by no means, the
only acceptable alternatives. WVDEP recognizes that every site is unique and that no one
guidance manual will be able to contain all of the scientifically valid methods of assessing and
remediating contaminated properties. VRRA encourages flexibility in remediating these under-
utilized and contaminated sites, both for the VRRA participant and for WVDEP. This section is
merely an overview of the requirements for the VRRA program. Details of the program are
provided in the following sections.
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Figure 1-1
WEST VIRGINIA VOLUNTARY REMEDIATION PROGRAM
-Overview-
Determine Site Eligibility
Pre-Application Meeting with
WVDEP (Mandatory for
Brownfields, Optional for Others) Hire LRS
Site Assessment
VRRA Application
Propose Clean-up Standards
Remedy Selection Using Evaluation
Criteria
Pay Application Fees Limited Liability Protection During
Good Faith Negotiations
Voluntary Remediation Agreement
Public Notification /
Involvement
LRS prepares Workplan / Submits
Additional Assessment, if Required
Remedial Design Schedule Oversight Fees
Implement Remedy
LRS Prepares / Submits
Final Report
Certificate of Completion
Issued if Final Report Approved
May Include Land Use Covenants
Reopeners
(See Rule § 60-3-16)
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1.1 General Structure of the Program
This section provides a summary of the requirements of the Voluntary Remediation
Program. Details concerning these requirements are provided in the subsequent sections and
appendices. WV’s voluntary remediation program has as its foundation the VRRA and the
associated Rule. Participation in the program may be initiated by the owner or operator of a site,
a developer, prospective purchaser, or other interested party. The purpose of participation is to
identify and address potential contamination at the site. Voluntary remediation also establishes
that the property complies with applicable remediation standards. Brownfield remediation is a
special case of voluntary remediation. Brownfield sites also are industrial or commercial
properties that are abandoned or inactive, however, voluntary remediation of brownfields
involves the use of public funds for the site assessment or remediation. Because of the use of
public funds, a much higher degree of public involvement is required for brownfield clean-ups.
Any person who wants to participate in the Voluntary Remediation Program must
execute a Voluntary Remediation Agreement with the Director of the WVDEP. The Voluntary
Remediation Agreement must provide for: 1) the services of a Licensed Remediation Specialist;
2) recovery of costs incurred by the WVDEP in excess of fees submitted by the applicant; 3) a
schedule for payment of recoverable costs; 4) descriptions of the work plan and other reports
that will be submitted; 5) a listing of applicable environmental requirements for the site; 6)
technical standards for work at the site; 7) any engineering or institutional controls or land use
covenants applicable for the site; and 8) criteria for reopening and modification of the agreement.
Once the Voluntary Remediation Agreement is executed, the Director is barred from
beginning any enforcement actions against the applicant for the site and contamination under the
agreement, unless there is an imminent threat to the public. The WVDEP is charged with the
overall administration of the Voluntary Remediation Program and its responsibilities are carried
out through the Office of Environmental Remediation (OER). The OER performs an oversight
function with respect to work that is performed through the Program. The oversight function
extends to review and approval of work plans and reports; periodic inspection of sites accepted
into the Program; access to and review of all records relating to activities under the Program and
performing sampling at sites in the Program. It is anticipated that the degree of OER oversight
will increase with the size and complexity of the site.
1.1.1 Responsibilities of the Licensed Remediation Specialist
Within the Voluntary Remediation Program, all activities must be supervised by a
Licensed Remediation Specialist. A Licensed Remediation Specialist (LRS) is a person
certified by the Director of the WVDEP as qualified to perform professional remediation
services and to supervise the remediation of contaminated sites.
The overriding duty of the LRS is to protect the safety, health and welfare of the public in
the performance of his/her professional duties. The LRS is responsible for any release of
contaminants from the site that occurs during approved remediation activities. If a release not
contemplated by the Voluntary Remediation Agreement occurs during remediation activities, the
LRS must immediately notify the WVDEP.
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It is expected that a single LRS will supervise all site remediation activities. The LRS
must be highly qualified, but it is unlikely that a single individual will have all of the skills and
knowledge to perform all activities associated with the remediation. The LRS must only perform
assignments for which he or she is qualified by training and/or experience in those specific
technical fields. He/she should seek assistance from other qualified professionals as needed in
performing work at the site.
The LRS is employed by the owner or developer of the contaminated site at usual and
customary professional rates. However, the LRS must be completely objective in developing
and reviewing work plans, reports, and opinions. The LRS represents the interests of the public
as well as providing technical supervision of all remediation activities.
1.1.2 Remediation Standards Concept
The Voluntary Remediation and Redevelopment Rules provides for a range of risk-based
soil, sediment and groundwater remedial objectives for site remediation. Risk-based remediation
standards allow for current and future land and water uses to be considered in the clean-up
process, while providing adequate protection of human health and the environment. The
incorporation of site-related information may allow for more cost-effective remediation based on
identified site risks.
1.1.3 Flexible Use of Remediation Standards Options
For any voluntary remediation, one or more remediation standards may be utilized. At
some sites, the property may have areas ranging from severely contaminated to nearly pristine.
For different sections of the property, different remediation standards may be appropriate. Under
the Rule, these risk-based standards are available: 1) De Minimis risk-based; 2) Uniform risk-
based; 3) site-specific risk-based; and 4) a combination of these remediation standards. The
flexibility of the Rule allows for standards to be utilized as appropriate for any particular site.
The VRRA recognizes that each site is unique and may require the use of valid scientific
procedures not specifically detailed in this guidance. In this case, the applicant and OER should
work together to develop mutually agreeable methodology.
Regardless of the remedial standard selected, selection of the remedial action is based on
achieving cost-effective protection of human health and the environment. In determining the
remedial action, applicants must consider and document the following criteria:
Effectiveness in protecting human health and the environment;
Long-term reliability of remedial actions in achieving the standards;
Short-term risks to the public, workers and the environment;
Acceptability of the remedial action to the affected community;
Engineering practicality of implementation;
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Achievement of protectiveness goals at lowest cost; and
Consideration of net environmental benefits.
Risk-based standards are derived considering the current use of the property or a
reasonably anticipated future use. Under the VRRA, the two categories of land uses are
residential and industrial. Industrial land use encompasses all kinds of commercial operations
including manufacturing, distribution, warehousing, and waste management. Residential land
use includes use of the land for homes, schools, nursing homes, recreation areas and the like.
Recreational exposure is similar to residential in areas such as parks and playgrounds due to
direct exposure to soils. Other recreational land use, such as gymnasiums and swimming pools
would not have these types of exposure and may be considered under the commercial/industrial
land use scenario. Please confer with the OER to determine if the exposure assumptions under
consideration are appropriate for a proposed land use. Current and future use assessments may
also include waters that may be part of or adjacent to the site. Different exposures and risks may
be present for land uses such as agricultural and forestry and may warrant site-specific analysis.
If land uses are being considered which involve exposure pathways not described in this
document, please confer with the OER for future guidance. It is recognized that different
exposures and risks may be present for these land uses and may warrant site-specific analysis.
1.1.3.1 Human Health Options
There are three options available for determining human health remediation standards. A
De Minimis Risk-Based Standard may be used where the contaminant concentrations detected
are below the risk-based concentrations provided in Table 60-3-B of the Rule and do not present
significant risk to human health. If De Minimis levels are below the natural background
concentrations, the natural background concentrations will be used as the De Minimis standard.
The De Minimis Standard assumes the applicant has completed the Applicable Standard
Checklist (Appendix C-1) to aid in determining whether the De Minimis Standard can be used
for their site.
A Uniform Risk-Based Standard uses pre-approved equations and exposure factors
identified in this Guidance Manual and other site-specific variable to calculate compound-
specific remediation levels. The uniform standard also assumes that the applicant has completed
the Applicable Standard Checklist (Appendix C-1), whether or not the site meets the De Minimis
standard. OER reviews the checklist in evaluating the remediation plan. Default assumptions
and equations for determining clean-up levels under the Uniform standard are located in
Appendix D-2. Exposure factors which may be replaced by site-specific information are also
listed in Table D-2.
A Site-Specific Risk-Based Standard uses a site-specific analysis of contamination and
develops a remedial approach that considers the criteria in Subsection 1.1.3. If the standards
developed in this way are below anthropogenic background levels of the contaminants at the site,
the background levels will be considered the site-specific risk-based level.
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A combination of these remediation standards may be used to implement a site
remediation plan. The rules allows for any of the above standards to be used. An applicant may
use site-specific risk-based standards whether attainment of other standards has or has not been
attempted. A more detailed discussion of these standards appears in Section 3 of this manual.
1.1.3.2 Ecological Options
Unlike human health standards, the ecological standards are a series of evaluations to
determine whether ecological receptors of concern are present and are affected. A De Minimis
Ecological Screening is the minimum evaluation to be completed on any site. Increasing levels
of assessment may need to be accomplished to assure ecological protection.
Where complete pathways to significant ecological receptors exist, the applicant may use
uniform “benchmark” levels as remedial goals, or may engage in a more elaborate, site-specific
ecological risk assessment to set site clean-up goals.
A De Minimis Ecological Screening Evaluation is an evaluation of the nature and
extent of contaminants on the site. The evaluation should determine if potential exposure
pathways are completed. If complete exposure pathways are not present between contaminants
and ecological receptors of concern, no significant risk to ecological receptors is assumed. If
complete pathways are present and the conditions outlined in Subsections 9.5.a through 9.5.b of
the Rule have been considered, additional evaluation of ecological risk may be required.
A Uniform Ecological Evaluation compares site contaminant levels to benchmark
values that pose no significant risks to ecological receptors of concern. If benchmark values are
below natural or anthropogenic background, background concentrations will be considered the
Uniform Ecological Standard. If an applicant proposes a remediation standard based on other
existing standards which exceed the benchmark values, the Director may require a site-specific
ecological risk assessment if he or she feels the other standards are not protective of the
ecological receptors of concern.
A Site-Specific Ecological Risk-Based Standard uses site-specific analysis of present
contamination and develops a remedial approach that considers the remedy criteria above. A
site-specific analysis may be conducted using guidance from Subsection 4.3 of this document.
1.1.3.3 Combining Human Health and Ecological Processes
A combination of human health and ecological standards may be used to implement a
complete site remediation plan. Parts of the site may be cleaned up to different standards. For
some sites or areas of a site, human health standards may be protective of ecological receptors as
well. At other areas, ecological standards may be the more stringent clean-up goal.
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1.1.4 Applicability of the VRRA to a Site
The Voluntary Remediation and Redevelopment Act can apply to almost any site in West
Virginia. For both currently operated and abandoned sites, the voluntary remediation program is
available. Sites eligible to participate in the program are those sites which are not:
subject to United States Environmental Protection Agency (USEPA) unilateral
enforcement orders under CERCLA (Comprehensive Environmental Response,
Compensation and Liability Act) or RCRA (Resource Conservation and Recovery
Act);
listed or proposed to be listed on the National Priority List (NPL) under CERCLA;
subject to WVDEP unilateral enforcement orders under Chapter 22 of the West
Virginia Code; or
created through gross negligence or willful misconduct.
Note: Sites that are covered by a federal or state consent order are not precluded from
participating in the Voluntary Remediation Program. In such circumstances, it would be the
applicant’s burden to assure that the requirements of both the consent order and the Voluntary
Program are satisfied.
A site may participate in the voluntary remediation program as a brownfield site if it
meets the general eligibility criteria for the program and:
the applicant did not cause or contribute to the site contamination;
the site was an industrial or commercial property either abandoned or not in active
use by the owner as of July 1, 1996; and
the applicant qualifies as a brownfield applicant by applying for or obtaining a site
assessment loan from the Brownfields Revolving Fund or by using other public funds
from the state, county, or municipality.
1.2 Sequence of Actions for Implementation of VRRA
To implement a remediation under the VRRA, a series of steps must be taken. After
eligibility for the program has been determined, the potential applicant should hire an LRS to
supervise site assessment and remediation activities and, if required (for brownfield sites) or
desired, request a pre-application meeting with the WVDEP. There is some flexibility in the
order in which some of these steps may be taken (see Figure 1-1).
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1.2.1 Site Assessment
Every application to participate in the Voluntary Remediation program must include a
site assessment. The VRRA allows considerable flexibility in the extent of the site assessment
that is necessary to support an application to participate. At a minimum, the site assessment
must include a legal description of the site, a description of the site’s physical characteristics, the
general operational history of the site, and any available information concerning the nature,
location, and extent of any known contamination on or near the site.
At some point, however, whether with the application or after the Voluntary Remediation
Agreement has been negotiated, sufficient information must be provided to assure that the site
has been adequately characterized both horizontally and vertically. Characterization under the
rule means an evaluation of the site’s physical and environmental features to determine: 1) if a
release has occurred; 2) levels of chemicals of concern in environmental media; and 3) likely
physical distribution of the chemicals of concern. Evaluation of the physical and environmental
features may include a review of subsurface geology, soil properties and structures, hydrology
and surface characteristics. Data are to be collected on groundwater and surface water quality,
land and resource use and potential receptors, both human and ecological. These data are
generated as appropriate to support remedial action decisions under the Program. Further
guidance on site characterization is found in Section 2.0.
1.2.2 Submission of an Application for Voluntary Remediation and Redevelopment of a
Site
To participate in the Voluntary Remediation and Redevelopment Program, an application
must be filed with the WVDEP. If the application is for a brownfield site, applicants must have a
pre-application conference with the Director and comply with loan procedures (Section 15 of the
VRRA Rule) before submitting an application. Other applicants may request a pre-application
conference with the Director, if desired.
An application form is available from the WVDEP Office of Environmental
Remediation. Applicants should submit the completed application to the Chief of the Office of
Environmental Remediation, 1356 Hansford Street, Charleston, WV 25301-1401. Each
application must be accompanied by an application fee made payable to the Voluntary
Remediation Administrative Fund.
The application fee is based on (1) the size of the property, (2) the years of operation for
non-residential purposes, and (3) the SIC (Standard Industrial Classification) Code for the
operations that occurred on the property. The fee will be determined using the point system
described below:
Size of Property
surface area less than one acre 10 points
surface area less than 5 acres and greater than 1 acre 20 points
surface area equal to or greater than 5 acres 30 points
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Years of Operation (for a non-residential activity)
10 years or fewer 10 points
more than 10 years but fewer than 20 years 20 points
20 years or more 30 points
SIC Codes (activities that may fall in more than one SIC Code will be assigned the code
with the highest points)
SIC 26 (Paper & Allied Products) 30 points
SIC 28 (Chemicals & Allied Products)
SIC 29 (Petroleum Refining)
SIC 30 (Rubber and Misc. Products)
SIC 31 (Leather & Leather Products)
SIC 33 (Primary Metals)
SIC 34 (Fabricated Metal Products)
SIC 35 (Industrial & Commercial Machinery)
SIC 36 (Electronic & Other Electrical Equipment)
SIC 37 (Transportation Equipment)
SIC 38 (Measuring, Analyzing & Controlling Equipment), and
SIC 39 (Miscellaneous Manufacturing)
SIC 10 thru 14 (Mining) 20 points
SIC 20 (Food)
SIC 21 (Tobacco Products)
SIC 22 (Textiles)
SIC 24 (Lumber & Wood Products, except Furniture)
SIC 27 (Printing & Publishing)
SIC 32 (Stone, Clay, Glass and Concrete)
SIC 46 (Pipelines) and
SIC 49 (Electric, Gas & Sanitary Service)
Any other SIC Code 10 points
Total points accumulated from the above criteria determine the application fee. The
application fees are:
Total points of 30 or 40 $1,000
Total points of 50 or 60 $3,000
Total points of 70, 80, or 90 $5,000
If the application covers two or more non-contiguous locations, the locations are similar
in terms of contaminants and surface/subsurface characteristics, and no one location is larger
than 2 acres, the application fee is $5,000. Any individual location with surface area greater than
2 acres requires a separate application and fee.
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1.2.3 Public Notification and Involvement
The WVDEP encourages participants in the voluntary clean-up program to communicate
with local government officials and interested members of the public regarding information
gathered and remediation plans for the site. Early, frequent and meaningful involvement of the
interested public with voluntary remediation activities can create a strong and cooperative project
that meets the needs of both the developer and the public.
While the discussion below lays out the minimum requirements for public notification
and involvement, focused and creative programs for public interaction with voluntary clean-up
activities are recommended. For simple and non-controversial sites (such as an abandoned gas
station), little public interest and, therefore, involvement might be expected. For a large,
complicated site, especially in highly populated areas, public interest and involvement is
expected to be much greater.
In cases where many stakeholders have strong interest in a site clean-up, a multi-pronged
approach to public participation may be warranted. For identifying public concerns, methods
such as public meetings, presentations to community organizations, advisory committees, site
visits and the like are often useful. If public input is to be used to develop ideas and solve
problems, small group meetings, field offices, requests for comments and ombudsmen are among
many public participation techniques that can be utilized. Stakeholder evaluation of remediation
proposals can be aided if the applicant provides such assistance as workshops, model
demonstration projects and environmental impact statements. Public participation activities can
also be helpful in resolving conflicts. More information about meaningful public participation
can be found in a variety of published documents including Ecology, Impact Assessment, and
Environmental Planning (Westman, 1985) from which some of the above information was taken.
Other resources for risk communication and public involvement guidance include:
USEPA Office of Chemical Emergency Preparedness and Prevention (CEPPO)
USEPA Superfund Office
Emergency Planning and Community Right-to-Know Act
(EPCRA) Hotline (800) 424-9436
USEPA Office of Policy, Planning and Evaluation (OPPE) (202) 260-4538
USEPA Risk Communication Hotline (202) 260-5606
USEPA Office of Pollution Prevention and Toxic Substances (202) 260-3944
Specific requirements of the VRRA relating to public notification and involvement
differentiate between brownfields and other voluntary remediation sites.
1.2.3.1 Brownfield Sites
The potential developers of brownfield sites, whether private or public entities, must
notify the public about remediation activities and provide for public involvement in planning for
remediation and redevelopment. The requirements are discussed below.
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Notice of Intent to Remediate
The brownfield applicant must file a Notice of Intent to Remediate with the Director of
the WVDEP. The WVDEP will publish a summary of the Notice of Intent to Remediate in a
WVDEP publication of general circulation and will issue a news release summarizing the Notice.
The summary will include information on the public’s right to know to become involved with the
development of remediation and reuse plans for the site. The news release will be sent to media
outlets covering the area of the remediation activity.
The WVDEP may also post the Notice on the Division’s Internet web site.
(http://charon.osmre.gov.)
In addition to these general methods of notifying the public, WVDEP will also directly
notify other government bodies of the Intent to Remediate. In the area where the brownfield site
is located, the municipality and county commission, any county or municipal land use agency,
and the Regional Planning and Development Council will be notified.
Depending on the site and its interest to state and federal agencies, WVDEP may also
notify the USEPA, the United States Army Corps of Engineers, the state Bureau of Public Health
and other state or federal agencies. All of these parties will be notified of the Director’s decision
on a Certificate of completion at the end of the remediation.
The Notice of Intent will contain the following information:
name and business address of the brownfield applicant; and
the geographic location of the site.
In addition, the Notice will include, as far as is known:
the current, former and proposed future uses of the site;
known and suspected contaminants on-site;
proposed methods to remediate the site; and
proposed methods for controlling possible health exposure.
For persons interested in the potential remediation, the Notice will also provide the
location where the Notice may be reviewed, and the names, addresses and telephone numbers of
the applicant’s public contact and the WVDEP contact for comments and questions.
The WVDEP Office of Environmental Remediation will make the Notice available for
public inspection and copying upon request. The Notice will also be available in the municipal
and/or county commission offices where the remediation is proposed and in the county library.
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A 30-day comment period and an informational meeting for interested parties are
required for all brownfield sites. The applicant must provide notice to the public of the start of
the comment period and of the informational meeting. This notice must be given in the
following ways.
by a 3’ x 4’ sign at the site stating “This site is under consideration for
environmental cleanup and participation in the state’s brownfield program
under the Voluntary Remediation and Redevelopment Act.” The sign will
include the WVDEP brownfield office address and phone number.
by a weekly 4” x 4” box ad in a local newspaper for 4 weeks which includes
the information from the Notice of Intent to Remediate plus the time, date and
location of the informational meeting.
by sending a copy of the box ad to local authorities and the county/municipal
land use agency, or the area’s Regional Planning and Development Council.
The WVDEP will draft the box advertisement and send it to the brownfield applicant for
publication. A certified and notarized proof of publication must be submitted to the WVDEP
within 4 weeks of the final publication date.
Anyone may file a request to participate in remediation and reuse planning. Interested
parties should write the Director during the 30-day comment period. By writing during the
comment period, interested parties may automatically participate, in person or by a
representative.
Brownfield Public Involvement Plan (PIP)
Each brownfield applicant must establish a PIP if requested by the public, by the county
or municipality where the site is located, or by the Director. The PIP is intended to make it easy
for the public to be involved with the planning for activities that may affect their communities.
The PIP will be developed by the applicant in consultation with those persons who have
requested to be involved in the remediation and reuse planning. The plan must be developed
within 30 days of receiving notice from the Director that a request to participate has been
received. The PIP will then be submitted to the Director for his/her review and approval.
The minimum requirements for a PIP include the following:
provisions for more community meetings;
opportunities for review and comment by participants on the work plan and
voluntary agreement; and
a means of communicating with the public which may include, but is not
limited to point of contact, mailing and telephone lists, newsletter, doorstep
notice, media advertisements, news releases, presentations, and a citizen
advisory panel for the remediation and reuse plan.
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Participants other than the applicant may petition the Director for technical assistance to
make their participation in remediation and reuse planning more meaningful. This technical
assistance may include review of site-related documents; explanations of technical information
and translation of technical jargon to layperson’s language; and assistance in communicating
concerns to the applicant, WVDEP or others. If the Director receives such a petition, the
Director and the brownfield applicant will, by mutual agreement, develop a technical assistance
component to the PIP, paid for by the applicant.
1.2.3.2 Voluntary Remediation Projects (non-brownfields)
Public Notice of Applications for Voluntary Remediation Projects
For voluntary remediation projects not involving a brownfield site, public notice must
also be given. Just as required for brownfields, WVDEP must publish a summary of the
application for voluntary clean-up in a WVDEP publication of general circulation and in a news
release to media outlets in the remediation area. The summary will include the following
information:
Name and address of the applicant;
Location of the site;
Current use of the site;
Suspected contaminants on site;
Proposed cleanup methods and proposed methods to control possible health effects;
Location where the application can be reviewed;
Name, address, phone number of applicant’s public contact person;
Name, address, phone number of WVDEP contact for comments and questions.
The Voluntary Remediation Application will be available for inspection and copying at
the WVDEP Office of Environmental Remediation and in municipal/county commission offices
where the project is located. Copies may also be placed in the county library. As additional
information is subsequently developed concerning the site, the DEP may elect to add such
information to the public repository.
Public Involvement and Notification in Development of Remediation Goals
Where a residual cancer risk level of greater than 1 x 10-6 is proposed for a residential
land use or greater than 1 x 10-5 for commercial or industrial use, an informational meeting and
30-day public comment period are required. Notification of the public will follow the steps
detailed in the previous sections for brownfield public notification.
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1.2.4 Remediation Standard Selection
Once it is determined following the site assessment that remediation of a site is
necessary, remediation standards are to be selected based on potential health effects, ecological
effects and current and reasonably anticipated future use.
1.2.5 Development of Risk-Based Concentrations
Risk-based concentrations under the Voluntary Remediation and Redevelopment Rule
must be based on scientifically valid toxicity information. This information may come from
recognized USEPA sources, from other government agency reports, or from peer-reviewed
scientific literature. Site-specific risk-based standards must consider the potential for exposure
to site contaminants under current and reasonably anticipated future land and water use.
For human health risk, carcinogen standards must be established at levels which represent
an excess upper-bound lifetime risk of between one in ten thousand (1 x 10-4) to one in one
million (1 x 10-6
). That is, the additional risk of cancer to an individual exposed to the site over a
lifetime of 70 years must not be greater than one in ten thousand to one in one million. All risk
estimates are to be expressed to only one significant figure.
Remediation standards for systemic toxicants must be contaminant concentration levels
to which the human population could be exposed without appreciable risk of harmful effects, that
is, where the hazard quotient does not exceed 1.0. Where multiple systemic toxicants affect the
same organ or act by the same method of toxicity, the Hazard Index (sum of the hazard quotient)
shall not exceed 1.0. Where multiple systemic toxicants do not affect the same organ, the
Hazard Index shall not exceed 10.0 (§60-3-9.4.b of the Rule). If the Hazard Quotient exceeds
1.0, further evaluations may be necessary as discussed in Section 3.4.1.3, Approach for
Calculating Noncancer Risks. All risk estimates are to be expressed to only one significant
figure.
1.2.6 Submittal of the Remedial Action Workplan
The applicant or the applicant’s LRS must submit any workplan required by the
Voluntary Remediation Agreement to the Director. The Director may approve or disapprove the
workplan, within 30 days of receipt, based on its quality and completeness. The Director may
require the following in a thorough remedial action workplan:
Health and Safety Plan;
Documentation of the investigation that led to preparation of the workplan;
Description of the assessments to be performed to further determine the nature
and extent of actual or threatened releases;
Description of the risk assessment conducted to show the appropriateness of
remedy selection;
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Statement of work to accomplish the remediation in accordance with the risk
protocol and remediation standards in the Rule;
Implementation schedule for the Remediation Workplan; and
Verification sampling plan to determine the adequacy of the remediation.
Within 5 days of a determination to disapprove a workplan, the Director must let the
applicant know of the disapproval and provide a list of the reasons for disapproval. The
Director will also indicate any additional information needed to gain approval. The applicant
must either resubmit the workplan or formally terminate the Voluntary Remediation Agreement.
If a final workplan is not approved or disapproved with 30 days of its receipt, the workplan will
be deemed approved.
1.2.7 Remedy Implementation
Following approval of the workplan, remediation activities may begin. Remediation
standards may be attained through one or more remediation activities that may include treatment,
removal, engineering or institutional controls, natural attenuation and/or innovative measures.
The West Virginia program is intended to be flexible and to allow innovation and good science,
but does not require unusual or novel procedures.
1.2.8 Closure/Remediation Verification
When the remedy implemented to meet the applicable standards is in place, the LRS may
prepare the Final Report. The Final Report should include all data and information needed to
document and verify that all applicable standards have or will be met. Any ongoing work and
monitoring must be described including planned activities and schedules. Supporting
documentation should be included. The LRS will submit the final report to the person or
organization undertaking the voluntary remediation.
1.2.9 Final Report Submitted for WVDEP Approval
The Final Report, if submitted by the applicant to WVDEP for approval, must include:
Names, addresses, telephone and fax numbers for the current owners and/or
operators of the site;
Names, addresses, telephone and fax numbers of the owners and/or operators
conducting the remediation and the LRS. Individual names and titles must be
provided;
Site location, its legal description and a site location map;
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Any ongoing work and monitoring must be described including planned
activities and schedules; and
Any institutional controls, such as deed restrictions or land use covenants,
must be confirmed by including copies of properly recorded documents. The
institutional controls must be shown on a site map.
The completeness and accuracy of the Final Report must be certified by an authorized
agent of the applicant and by the LRS. The LRS and the applicant’s agent may be the same
person. The certified Final Report may be submitted to the Director for approval with a request
for a Certificate of Completion. Upon review of the final report, the Director determines
whether it was properly issued.
1.2.10 WVDEP Issuance of Certificate of Completion
When the Director receives a request for a Certificate of Completion, he/she must
determine if the site meets the proper requirements. These requirements are that the applicable
standards for the areas and contaminants covered by the Voluntary Remediation Agreement have
been met, and that the applicant has complied with the Agreement and approved work plans for
the site. The Director must determine that the Final Report was properly issued within 60 days
of the submission of the request for a Certificate of Completion.
If the Director determines that the Final Report was properly issued, a Certificate of
Completion must be issued within 30 days of his/her decision. If the report was not properly
issued, the Director must promptly notify the applicant in writing. The notification will include
the reasons why the report was not approved and will indicate any further actions necessary for
issuance of the Certificate.
An applicant who receives a notice of disapproval may take one of the following steps.
The applicant may: 1) instruct his or her LRS to take the further actions as indicated in the
notification; 2) appeal the Director’s decision to the Environmental Quality Board; or 3)
formally terminate the Voluntary Remediation Agreement.
The successful applicant will receive a Certificate of Completion for the remedial
activities covered under the Voluntary Remediation Agreement. A Certificate of Completion
will incorporate the following information:
Description of the site;
Description of contaminants for which the standards have been met;
The Voluntary Remediation Agreement;
The Final Report prepared by the LRS; and
Any land use covenant or deed restriction including, where applicable, a
description of any institutional or engineering controls required for the site.
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The Certificate of Completion will certify that:
the site meets the applicable standards; and
the applicant, current and future owners and occupiers and their successors,
public utilities, remediation contractors, the LRS, and lenders:
1) are relieved from liability to the state for the release that caused the
contamination, and the state shall not bring civil, criminal or
administrative action as long as the site meets the standards in effect at the
time the certificate was issued, and
2) shall not be subject to citizen suits with regard to the contamination that
was the subject of the Voluntary Remediation Agreement.
The Certificate of Completion becomes effective upon signature by the Director or, if
applicable, when any land use covenant is filed, whichever occurs last.
1.2.10.1 Certificates of Completion Issued by Licensed Remediation Specialist
Under certain circumstances, a Certificate of Completion for a completed remediation
project may be issued by the LRS in charge of the site. The LRS, after assuring the site is
eligible for the Voluntary Remediation Program, must issue a final report to notify the Director
of his or her intent to issue a Certificate of Completion when the remediation is complete.
When the LRS is sure that the site meets the De Minimis Risk Based standards for
Human Health and passes the De Minimis Ecological Screening Evaluation, he or she may issue
the Certificate to the owner of the site. The Certificate of Completion will be similar to the
forms used by the WVDEP (sample form available in Appendix 60-3 of the rule).
The Director may object to the issuance of a Certificate of Completion by a Licensed
Remediation Specialist. Following notification by the LRS that he/she intends to issue the
Certificate, the Director has 30 days to object. If the Director fails to object within this time
period, the Certificate of Completion may be properly issued by the LRS.
If the Director objects to the issuance of the Certificate of Completion by the LRS, the
applicant may: 1) appeal the decision to the Environmental Quality Board; 2) undertake further
actions identified by the Director as necessary to cause the Certificate to be issued; or 3)
terminate the Voluntary Remediation Agreement.
A Certificate of Completion issued by a LRS becomes effective when signed by the LRS
(after notice to the Director as described above), or if applicable, when any land use covenant is
filed, whichever occurs last.
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1.2.10.2 Reopeners
The protections of the Certificate of Completion are transferable beyond the current
owners. It is possible that the property, at sometime in the future, may not satisfy the obligations
of the Certificate and the Voluntary Remediation Agreement. For instance, if a site received its
Certificate of Completion based on achievement of risk-based standards for an industrial use, and
in the future, the then current owner converts the site to residential use, the approved standards
for the site are no longer being met. Under conditions such as these, the Director must begin
actions to rescind the covenant as it applies to the then current owner and/or operator and must
insure that the site is brought into compliance.
The Certificate of Completion also may be revoked or further remediation required if the
Director determines that a reopener has been triggered. Reopeners include:
Fraud – There is evidence that fraud was committed in regard to attainment of
standards set forth in the Voluntary Remediation Agreement.
New Information – New information confirms the existence of previously
unknown contamination within the site and that contamination exceeds the
standards in the Voluntary Remediation Agreement.
Increased Level of Risk – If the level of risk at a site is significantly increased
beyond the level of protection established through the Voluntary Remediation
Agreement. This could occur as a result of substantial changes in exposure
conditions, including changes in land use or new information about
contaminants that revises exposure assumptions. Significantly increased risk
means the level of risk has increased by a factor of five or the hazard index
exceeds the criteria listed in Section 1.2.5 of this Guidance Manual.
Release after July 1, 1996 – The release addressed by the Voluntary
Remediation Agreement occurred after July 1, 1996, on a site that was not
used for industrial activity before that date, and 1) the remedy selected for the
remediation relied, in some aspects, on institutional or engineering controls,
and 2) treatment, removal or destruction of the contaminant has now become
technically and economically practical.
Remediation methods failed to meet remediation standards – The remediation
methods employed on the site failed to meet the remediation standard(s) in the
Voluntary Remediation Agreement.
1.3 Interaction of the Voluntary Remediation Program With Other Environmental
Programs
The VRRA contemplates that remediation performed under it will satisfy the
requirements of all environmental statutes administered by the WVDEP. It is the responsibility
of the Office of Environmental Remediation, through the provisions of each VRRA and the work
plans submitted for its approval, to assure that this goal is achieved.
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1.4 References
United States Environmental Protection Agency (USEPA). 1994. Risk
Assessment, Management, Communication: A Guide to Selected Sources.
EPA/749B-94-001. Office of Pollution Prevention and Toxic Substances.
Westman, W.E. 1985. Ecology, Impact Assessment, and Environmental
Planning. John Wiley & Sons, N.Y. 532 pp.
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2.0 SITE ASSESSMENT
The applicant must perform a site assessment to identify actual or potential contaminants
at the site. The site assessment should provide the Director with sufficient information about the
site to allow for evaluation of whether it is eligible for the program, but may not be complete
enough to describe the full extent of contamination. Some applicants may prefer to perform a
more extensive site assessment before filing an application while others may want to perform a
more complete characterization after a voluntary agreement with the Director has been executed.
The advantages to completing the site assessment after the agreement is executed are: protection
against enforcement actions are in place and the applicant can seek input from the agency on the
next phases of the site assessment.
At a minimum the site assessment should include the following information:
Site History - A brief description of historical operations and regulatory status
to enable the Director to evaluate eligibility. The site history should also
describe land and water resource uses on site and in proximity to the site.
Conceptual Site Model - The model is based on historical site usage and
analytical data from sampling of soils, media of concern (e.g., groundwater or
surface water). The conceptual model identifies actual and expected
chemicals of potential concern (COPCs), the nature and extent of
contamination, the pathways for migration of contamination, and the potential
receptors.
Sampling and Analysis Plan - The sampling and analysis methodologies and
quality control procedures should be described or in the case where no
sampling is planned, justification for not sampling should be provided.
Analytical Data - Samples of environmental media should be collected in
order to describe the physical and environmental setting and support the
conceptual model. The sampling should be conducted to determine: if a
release has occurred, the concentrations of COPCs in the environmental
media, and the physical descriptions of the COPCs.
The following sections describe in more detail the components of the site assessment
described above.
2.1 Site Characterization Objectives
The objectives of site characterization are as follows:
(1) Identification of potential site-related contaminants reasonably expected to be at
or near the site.
(2) Determination of the presence or absence of those contaminants in the media of
concern.
(3) Identification of the nature and extent of contamination.
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Figure 2-1: Site Assessment Process
Develop Sampling and Analysis Plan
(SAP) for Soils and Groundwater
Develop Preliminary
Conceptual Site Model
Conduct
Additional
Investigations
Identify Potential
Sources of Contamination
Conduct Field
Investigation
Evaluate
Analytical Results
Prepare
Justification
For No Sampling
Review Site History /
Past Operations
Refine Conceptual
Site Model
Submit Site
Assessment to Agency
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(4) Identification of potential pathways for contaminant migration.
(5) Identification of the potential receptors of the contamination.
The process through which site characterization will proceed is illustrated on Figure 2-1.
In many cases site characterization will be an iterative process that will continue until adequate
data is developed to allow for evaluation of potential risks posed by the site and/or appropriate
remedial alternatives for the site.
This section of the Guidance Manual was prepared to assist the LRS in meeting the above
listed objectives. This Guidance Manual was not intended to restrict the methods by which site
characterizations are performed. Rather, it was intended to provide a framework to assist the
LRS in development of a work plan for a site characterization and to provide a listing of other
guidance documents that may be helpful in the design of an effective site characterization
program.
2.2 Preliminary Characterization
Site characterizations should generally be initiated with a literature review and brief site
visit by the LRS (i.e., a preliminary characterization). The three primary areas of research
during the preliminary investigation should include a review of the following: (1) information
about the site history to identify the COPCs and anticipated areas where those chemicals have
been handled, (2) information about the physical characteristics of the site that may influence the
distribution and migration pathways of the COPCs, and (3) a listing of the potential
environmental receptors and associated exposure pathways. This information will be used to
develop the conceptual site model.
2.2.1 Evaluation of Historical and Current Land Uses to Identify COPCs
The scope of work for the historical investigation will depend on the nature of the
property (e.g., gasoline station versus chemical plant) and the requirements of the potential
property buyer/developer. The American Society for Testing and Materials (ASTM) has
developed a generally accepted standard for historical research of properties titled “ASTM E
1527-974 Standard Practice for Environmental Site Assessment: Phase I Environmental Site
Assessment Process”. The ASTM procedure includes: (1) review of government databases, (2)
review of historical use information, (3) interviews with people who are knowledgeable about
the site, (4) interviews with government officials, (5) review of physical setting references (e.g.,
a United States Geological Survey [USGS] topographic map), (6) review of existing site-specific
environmental data and (7) a site reconnaissance.
Government data reports can be obtained directly from the agencies or through private
firms who specialize in database tracking. Examples of the federal databases that are available
include, but are not limited to: the NPL, CERCLA list (CERCLIS), RCRA Treatment, Storage
and Disposal (TSD) Facilities list, RCRA Generators list, and the Emergency Response
Notification System (ERNS) list.
Other valuable sources of information include, but are not limited to: existing
environmental investigation reports, operational maps, references in local libraries, Sanborn fire
2 - 4
insurance maps, chain of title information, aerial photographs, 100-year flood plain maps, and
other such records.
If possible, people who are knowledgeable about the site (e.g., plant managers, former
employees) should be interviewed. The interviews should focus on the identification of the
COPCs and where they had been handled. Topics of discussion could include: availability of
historical and current site maps, locations of former underground and/or above ground tanks,
locations of underground utilities or septic systems, transformers, waste piles, drum storage
areas, historical releases, compliance history, knowledge of adjacent properties, and so forth.
In addition to interviews with site personnel, it may be appropriate to contact government
officials (e.g., WVDEP, fire department, local city engineer, USEPA). The government officials
may have knowledge or records of accidents and/or the compliance history of the site. For
review of the files maintained by the WVDEP, you should contact the Public Information
Office at (304) 759-0515.
One or more site visits should be performed by the LRS or authorized representative to:
confirm the accuracy of available mapping, to confirm information obtained during the historical
reviews and interviews, and to look for visual evidence of potential contamination sources (e.g.,
stained soils, fill/vent pipes from underground storage tanks (USTs), stressed vegetation, drums,
waste piles, etc.). It is beneficial to have a knowledgeable former site employee participate in
the site visit to identify potential areas of concern to the LRS.
2.2.2 Preliminary Evaluation of Site Physical Characteristics
Requirements for the written description of the site are specified in Section 4.2.f of the
Rule. The written description should include (1) the site address, (2) significant landmarks (e.g.,
nearby roads, surface water bodies, wetlands, buildings), (3) tax map references, (4) deed book
and property number, and (5) site survey coordinates. The survey coordinates may be provided
using the Universal Transverse Mercator (UTM) zone 17 NAD datum (preferred), geographic
latitude and longitude, or the State Plane Coordinate System (NAD 27 datum). The site map
must be accurate to within 12.2 meters (40 feet).
The site location should be shown on a large scale map (e.g., USGS 7.5 minute
quadrangle) as well as a smaller scale map that shows major site features (e.g., buildings, streets,
tanks, water wells, gas wells). For large and complex sites, it may be appropriate to have a
surveyed topographic base map prepared for the site. For smaller sites, a simple scaled sketch
may suffice.
In addition to documentation of the surficial site features, information about the
subsurface conditions may need to be developed. Topics to be considered may include, but are
not limited to:
Characteristics of the site soils (grain size, permeability, ability to drain)
Depth to bedrock
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Site stratigraphy
Bedrock characteristics/lithology/fractures
Significant structural features (e.g., faults, folds, sink holes)
Depth to groundwater
Predicted direction of groundwater flow
Relative permeability of the site formations, aquifer, confining layers
How water is removed from the site (e.g., evaporation, runoff, infiltration)
Aquifer thickness
Presence of water bodies (e.g., lakes, ponds, streams, springs, wetlands)
Prediction of probable migration pathways for the COPCs
Relationship between groundwater hydraulics and surface water features
Aquifer properties (e.g., hydraulic conductivity, transmissivity)
Initially this information could be developed by review of existing investigation reports,
published literature, as well as information gathered during the site reconnaissance by a geologist
or qualified LRS. Published references concerning local and regional soils, geology and
hydrogeology can be obtained from local libraries, the USGS, the State Geological Survey,
and/or the United States Department of Agriculture (USDA).
If information about the physical characteristics of the site is not developed, the LRS
should present the reasons why such an assessment was not necessary (e.g., the only COPCs are
inside a building - for example asbestos insulation - and do not realistically represent a threat to
the other site media).
2.2.3 Preliminary Identification of Potential Human and Ecological Receptors
A preliminary identification of potential human and ecological receptors will need to be
established prior to evaluation of the risks that may be posed by the site under existing and/or
future land use scenarios. The checklist in Appendix A guides the applicant in identifying
receptors. This initial evaluation should consist of a literature review and site visit by the LRS or
his or her representative. During the site visit, the following general items should be described:
Current and likely potential future land uses
Site structures, including access restrictions (e.g., fencing, locked gates,
natural barriers)
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Any visible signs of trespassers
Approximate percentage of grass/exposed soil areas, paved areas, and
buildings
Location, distance to, and description of on-site and adjacent water bodies
(e.g., streams, rivers, lakes, swamps)
Surface soil type (e.g., sandy, silty, exposed or vegetated)
Visible signs of contamination (e.g., stained soils, stressed vegetation)
Potential migration pathways off-site and/or to sensitive environments (e.g.,
drainage patterns, topography)
Observed flora and fauna
More thorough investigations (e.g., wetland delineations) may be required if identified
receptors potentially may be impacted by site activities.
The following two sections present items that are specific to the identification of potential
human and ecological receptors. After this information is gathered, it is important to combine
this data with information collected following the procedures described in Sections 2.2.1 and
2.2.2 to determine if contaminant migration pathways to the receptors or sensitive environments
are possible. If migration to a receptor or sensitive environment is possible, then a study (e.g.,
sampling and/or risk assessment) may need to be conducted to further evaluate potential impacts
to the receptor of potential concern.
2.2.3.1 Human Receptors
In addition to the general items presented above, specific items related to human
receptors should be researched. Some of the specific items to be evaluated are as follows:
Describe the current and reasonably foreseeable future use of the site (e.g.,
residential, commercial, industrial). This will be used to estimate the amount
of time human populations (including adults and children) are currently
present on site and potentially may be present on site. In addition, describe
the current use of the area surrounding the site and closest off-site human
receptor(s), and sensitive populations (e.g., schools, hospitals, retirement
homes).
Identify the source for the local drinking water supply (e.g., groundwater,
springs, and surface water). Also identify if the drinking water supply is
public, private, or both (i.e., some houses that are connected to public water
supplies also may have a private well). This information may be obtained
from the local water authority, health department, state and/or USGS. A door-
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to-door well survey may be necessary in some instances (e.g., if contaminated
groundwater is migrating off site towards potential human receptors).
Identify any known or anticipated recreational activities (e.g., recreational
fields, playgrounds, fishing, swimming, boating) that may result in an
increased potential for human exposure.
Identify the location of septic tanks and leach fields and note proximity to
water wells.
The above data can be investigated during the site visit, through a review of the zoning
records, conversations with residents, and correspondence with the appropriate state or local
government offices. In addition, this information may be available from previous investigations
for the site or surrounding areas, USGS topographic maps, and other literature/maps.
2.2.3.2 Ecological Receptors of Concern
Ecological receptors of concern are defined as specific ecological communities,
populations, or individual organisms protected by federal, state or local laws and regulations or
those local populations which provide important natural or economic resources, functions, and
values. The ecological assessment portion of this preliminary evaluation consists primarily of a
literature review and a site visit to determine the presence or absence of ecological receptors of
concern that potentially may be impacted by contaminants originating from the site. Significant
ecological investigations (e.g., fish surveys, endangered species surveys, jurisdictional wetland
delineations) are not anticipated to be conducted as part of this preliminary evaluation.
More detailed ecological investigations may be required if the preliminary evaluation
concludes that there may be impacts to potential ecological receptors of concern. The presence or
absence of the valued environments listed below should be considered when identifying potential
ecological receptors of concern since they may represent habitat for populations which provide
important natural or economic resources, functions, and values. More detail is provided in
Subsection 4.1.4 of this Guidance for identifying ecological receptors of concern.
Surface water bodies or wetlands that function as feeding, breeding, nesting,
resting, or wintering habitat for migratory waterfowl or other aquatic birds
Surface water bodies or wetlands that function as spawning or nursery areas
critical for the maintenance of fish/shellfish species
Critical habitat for federal or state designated threatened, endangered, or
otherwise protected species as defined in 50 Code of Federal Regulations
(CFR) 424.02
Habitat known to be used or potentially used by federal or state designated
threatened, endangered, or otherwise protected species
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Area designated as a National Preserve
Federal land designated for protection of natural ecosystems
Designated or administratively proposed Federal Wilderness Area
National or State Parks or Forests
National or State Wildlife Refuges or other wildlife management areas
State-designated natural area
Climax community (the final successional stage of constant species
composition such as an old growth forest)
Areas important to the maintenance of unique biotic communities
Critical areas identified under the Clean Lakes Program
Federal or State scenic or wild river
Trout-stocked streams or wild trout streams with verified trout production
Federal or State fish hatcheries
National river reach designated as recreational
Breeding areas for dense aggregations of birds, mammals, amphibians, or
reptiles
Other Federal, State, or local-Designated Critical Biological Resource Areas
or Conservation Areas
Other valued environments not listed above that may be noted during the site
visit or literature search.
During this preliminary evaluation, most of this information may be obtained by
contacting the appropriate federal or state agency. The following agencies may be contacted to
obtain some of the above information. It should be noted that this list is not inclusive of all
agencies that may be able to provide information about valued environments.
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WV Division of Natural Resources (WVDNR), Charleston, WV
(http://www.state.wv.us)
WVDEP, Nitro, WV (http://www.state.wv.us)
WVDNR, Natural Heritage Program, Elkins, WV
(http://www.abi.org/nhp/us/wv/index.html)
U.S. Fish and Wildlife Service, Elkins, WV (http://www.fws.gov)
National Park Service, Washington DC (http://www.nps.gov)
Nature Conservancy, Washington DC (http://www.tnc.org )
A site visit is necessary to initially evaluate the presence of items that may not be
identified in the literature (e.g., small water bodies, or wetlands). The site visit also is important
to better identify potential contaminant migration pathways from the site to ecological receptors
of concern and valued environments. Consideration should be given to development restrictions
and/or permits that may need to be obtained if site activities potentially could impact valued
environments (e.g., development in wetland areas, alteration of endangered species habitat).
Refer to Subsection 4.1.4 for details on ecological site characterization and management goals.
2.2.4 Develop a Conceptual Site Model
The conceptual site model will be used for development of the sampling program, risk
evaluation, and remedial design. Because of the model’s importance to all aspects of the project,
it should be developed early in the project. The purpose of the model is to provide a visual
representation of and to identify the following:
Anticipated contaminants (e.g., volatile organics, metals, pesticides,
explosives, petroleum)
Primary and secondary source areas (e.g., residual chemicals in abandoned
tanks, lagoons, sumps, contaminated soils)
The release mechanism (e.g., leaking tanks, infiltration of precipitation
through contaminated soils)
Potential migration pathway(s) (e.g., groundwater, wind blown, river
transport, utility conduits)
Anticipated media of concern (e.g., soil, groundwater, surface water,
sediments, air, building materials)
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Potential exposure pathways (e.g., leaching, percolation, groundwater
transport)
Potential receptor(s) of concern (e.g., humans, fish, birds)
Ecological interactions
The conceptual site model is developed based on:
Historical information about former site activities (particularly with respect to
the handling and management of chemicals)
Information about the physical and chemical characteristics of the media of
potential concern, that will influence the distribution and migration pathways
of the contaminants of concern
A listing of the environmental receptors of potential concern
Note: It is important that the conceptual site model initially include all sources, media and
exposure pathways that are of reasonable or at least plausible concern, now or in the future.
As the investigation proceeds and additional data are generated, the conceptual site model
will be refined. At that point certain source areas and pathways can be excluded from the model,
as appropriate. It is essential that when such exclusions occur that the rationale is documented in
the text of the conceptual site model. Also the model text should clearly indicate which
pathways of exposure were quantified in the risk assessment. In an adequately developed site
conceptual model, a reviewer can easily determine which pathways have been addressed in the
quantitative portions of the risk assessment and which have been addressed qualitatively.
It may be helpful to illustrate the site conceptual model through various figures (e.g.,
hydrogeologic cross sections and/or pathway analysis diagrams). Figure 2-2 is an example of a
pathway analysis diagram for a hypothetical site that has completed some initial phases of
investigation. Figure 2-3 illustrates a more complex site, which has more data available for
consideration in the conceptual site model. These illustrations can help the LRS and project
team evaluate the best way to eliminate the existing potential exposure pathways and identify
data gaps which will require further evaluation. The model can also be used as a communication
tool for public interaction.
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The LRS generally can develop a reasonable conceptual model after completion of
historical and geological research about the property and after conducting a site reconnaissance.
However, the conceptual model will need to be modified/updated, as more data becomes
available. Site investigations may require multiple phases of sampling and testing before the
model is complete enough to select design and implement an appropriate remedial strategy
and/or before the risks posed by the site can be fully evaluated. However, a well-defined
conceptual model will aid in acceleration of remediation and redevelopment of the site.
2.2.5 Risk Evaluation
The conceptual site model will provide the framework for evaluation of risks that may be
posed by the site. The risk evaluation is an integral part of the site characterization process, and
will guide what, if any, remedial actions will be taken at the site; and ultimately how and when
the site can be put back into productive use. The format and complexity of the risk evaluations
will depend on the site characteristics as defined in the conceptual site model. Guidance on how
the risk evaluations are to be performed is provided in Chapters 3, 4, 5, 6, 7, and 8.
2.3 Develop Data Requirements for Sampling and Analysis Plans
The exact nature of the sampling and analysis plans (SAP) will be highly dependent on
the quality and amount of analytical data available at the time a site enters the VRRA program.
In some cases, site investigations may have been completed prior to entering the program. If the
investigations are complete at the time of application into the program, the Director will need
adequate documentation of the work performed. Although not required, it is generally beneficial
for the LRS to discuss the SAP with the WVDEP prior to implementation to avoid rework that
may later be requested by the Director.
Prior to development of the SAP, the site specific data requirements will need to be
determined. The primary driver for determination of the analytical data requirements will be the
risk evaluation requirements. In particular, the site investigation will need to quantify the
concentrations of the COPCs in the media of concern at detection levels low enough to allow for
evaluation of the data for the reasonably anticipated exposure scenarios. The data may also be
needed for preparation of a remedial action plan or to support contaminant transport modeling to
determine if the data indicates a potential for human health, or ecological risks, and/or exceed
regulatory criteria.
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FIGURE 2-2: EXAMPLE CONCEPTUAL SITE MODEL FOR HYPOTHETICAL ABANDONED SERVICE STATION
Primary Primary
Source Release
Mechanism
Secondary
Secondary Release Pathway Sources
Mechanism Exposure
Route
Area
Residents
Site
Workers
Terrestrial
Aquatic
SITE HISTORY SITE PHYSICAL CHARACTERISTICS ENVIRONMENTAL RECEPTORS
HUMAN BIOTA
Dust and/or
Volatile
Emissions
Wind
Ground
water
Surface
Water and
Sediments
Stormwater
Runoff
Infiltration/
Percolation
Soils
Spills /
Leaks
Drums and
Tanks
Ingestion
Inhalation
Dermal
Ingestion
Inhalation
Dermal
Ingestion
Inhalation
Dermal
Pathway not complete.
Pathway is or may be complete; however, risk is low.
Pathway is complete and may be significant.
2 - 13
FIGURE 2-3: EXAMPLE CONCEPTUAL SITE MODEL FOR HYPOTHETICAL ABANDONED INDUSTRIAL RIVER FRONT PROPERTY(a)
SITE HISTORY SITE PHYSICAL CHARACTERISTICS ENVIRONMENTAL RECEPTORS
Historical
Operations
Contaminants of
Concern
Primary
Release
Mechanism(s)
Potential
Source
Areas
Fate and
Transport
Mechanisms
Media of
Concern
Current or Future
Exposure
Pathways
HUMAN BIOTA
Area Residents(b)
On-Site Worker
Area and /or Site Visitor
Terrestrial
Aquatic
Chemical
Manufacturing and Handling
Pesticides
Spills During Tank Car Loading
Contaminated Soils
Leaching/ Adsorption
Soil
(surface and subsurface)
Dermal
Oral
Inhalation
Percolation Recharge
Groundwater Transport
Groundwater (no
wells on site wells located off site)
Dermal
Oral
Inhalation
Discharge
Discharge
Adsorption onto Sediments
Sediments
Dermal
Oral
Inhalation
Desorption
Disperson / Dilution Below Detection in Surface Water
Fuel Storage
BTEX and
PAHs
Leaking UST
UST
Tank
Removal
Free Product
Dermal(b)(c)
Oral(b)(c)
Inhalation(b)(c)
Contaminated
Subsurface
Soils
Leaching/
Adsorption
Subsurface Soils
Dermal(b)
Oral(b)
Inhalation(b)
Percolation Recharge
Groundwater
Transport
Groundwater
Dermal
Oral
Inhalation
Attenuation
Adsorption and Biodegradation to Concentration Below Detection
Weathering /
Deterioration
Existing Pipe
Insulation
Vapor Transfer to
Building Basement
Air
Inhalation
Process Piping Asbestos
Demolition
Surface Soils
Wind
Air
Inhalation
Legend Notes:
Pathway not complete. No Evaluation Necessary (a) Model based on site with some environmental sampling data.
Pathway is or may be complete; however, risk is low: Qualitative evaluation only. (b) Model assumes that future development scenarios will be limited to commercial and industrial options. Residential development will be controlled by deed restrictions.
Pathway is complete and may be significant: Quantitative evaluation necessary. (c) Potential exposure during tank removal by trained and adequately protected hazardous waste workers.
The following sections describe some of the data considerations for risk assessment,
remedial design and modeling.
2.3.1 Risk Assessment Data Requirements
Risk assessments should be performed in general accordance with Chapters 3 to 8 of this
guidance. A comparison to De Minimis standards, uniform risk-based standards or site-specific
risk-based standards may be conducted. Typical data required to perform the risk evaluation are
as follows:
Field investigation data (e.g., source testing, media sampling), especially with
respect to:
- Background constituent concentrations by media (either naturally
occurring or anthropogenic concentrations)
- Site-specific constituent concentrations by media
- Quantification of present and future exposures (e.g., exposure
pathways; present and potential future land use; media that are or may
be contaminated; locations of actual and potential exposure; and
present concentrations at appropriate exposure points)
- Potential receptor information
- Type and duration of possible exposures (e.g., chronic, intermittent)
- Environmental setting (e.g., climate, geology, hydrogeology,
topography, nearby surface water)
Appropriate data for statistical analysis (e.g., sufficient data to satisfy
concerns about distributions of sampling data and statistics)
Exposure assumptions (e.g., exposure duration, typical body weight, ingestion
rate)
Data needs for fate and transport models (see Section 2.3.3)
Data evaluation/usability, especially with respect to
- COPCs
- Analytical quantification levels
Data validation of analytical data
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Toxicity information (e.g., reference dose [RfD], reference concentration
[RfC], cancer slope factor [CSF])
Further details on the data requirements for risk assessment may be found in the
references listed below:
USEPA. 1989. Risk Assessment Guidance for Superfund Volume I. Human
Health Evaluation Manual (Part A) Interim Final. Office of Solid Waste and
Emergency Response (OSWER). Washington, D.C. EPA/540/1-89-002.
March 1989.
USEPA. 1992. Guidance for Data Usability in Risk Assessment (Part A)
Final. Office of Emergency and Remedial Response. Washington, D.C.
Publication 9285.7-09A. April 1992.
USEPA. 1989. Risk Assessment Guidance for Superfund, Volume II:
Environmental Evaluation. OSWER. Washington, D.C. EPA/540/1-89-001.
March 1989.
USEPA. 1995. Land Use in the CERCLA Remedy Selection Process. Elliott
P. Laws, Asst. Administrator. OSWER Directive 9355.7-04. May 25, 1995.
USEPA. 1997. Integrated Risk Information System On-line Database.
Environmental Criteria and Assessment Office. Cincinnati, Ohio, 1997.
2.3.2 Data Requirements for Remedial Action Design (if applicable)
The objective of data collection for remedial action design is to provide the LRS with the
necessary information to complete the following tasks:
Screening of potentially applicable technologies
Evaluation of the cost, effectiveness, and implementability of applicable
technologies
Development of the detailed design parameters associated with the scope,
duration and operation of the remedial action and remediation system.
Physical and chemical characteristics of the media of concern, that require remedial
action, should be compiled as early as possible. Consideration of the data requirements for
technology selection and design during preparation of sampling and analysis plans can reduce
sampling costs by avoiding remobilization and inefficient data collection, while expediting the
evaluation of appropriate remedial technologies. Evaluation of remedial alternatives early in the
site characterization process will aid in identifying data gaps that may delay or prevent
remediation and site closure.
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Data requirements for soils typically include the traditional engineering properties of
soils, data on soil chemistry, vertical and horizontal contaminant profiles, and the overall range
and diversity of contamination across the site. Analytical data requirements for water (usually
groundwater) may include chemistry, oxygen demand, pH, flow volume, flow direction, and/or
other parameters. Because of the turbid nature of some samples from temporary wells,
questionable results for metals analysis may not be useable data for risk assessment.
Remedial technologies can be grouped into five general categories, which are: thermal,
physical, chemical, biological, and stabilization. These categories and some of the specific
treatment alternatives associated with these categories are briefly introduced in Section 7 of this
guidance. The tables that accompany this section present in matrix form some of the
characteristics of the media to be treated that can impact the selection of a particular treatment
category or treatment alternative.
Table 2-1 lists soil characteristics which can be investigated during site characterization
to support technology selection, with a general interpretation of the meaning of high and low
values for each characteristic. Table 2-2 provides similar information for water-related treatment
categories. Engineering input should be obtained on a site-specific basis prior to the preparation
of sampling and analysis plans or selection of treatment alternatives.
The USEPA’s Engineering Bulletin “Technology Pre-selection Data Requirements,”
EPA/540/S-92/009 (USEPA 1992) can be reviewed for additional information related to data
requirement for remedial design. The Engineering Bulletins are series of documents that
summarize the latest information available on selected treatment and site remediation
technologies and related issues. Information is also available from the USEPA’s “Guide for
Conducting Treatability Studies under CERCLA.”
Cleanup professionals who need current information on remediation
technologies can access the USEPA’s Cleanup Information Bulletin Board
System CLU-IN online at www.clu-in.org and www.clu-
in.org/remdtext.html.
2.3.3 Data Requirements for Modeling (if applicable)
The objective of a model is to predict whether or not site contaminants (pre- and/or post-
remediation) will create a condition that will impact a receptor of potential concern above risk-
based acceptable criteria. A conceptual site model as discussed in Section 2.2.4 is required for
all sites. Other types of models can also be used to assist the LRS in selection of the most
appropriate remedial design. Mathematical models are not applicable to all sites. Generally,
they can best be performed after significant site-specific data have been collected.
Soil models may be used to demonstrate that residual soil contamination will not impact
the quality of groundwater beneath the site above the risk-based concentrations. Groundwater
models may be used for many types of demonstrations including:
2 - 17
Groundwater flow modeling to illustrate that receptors will not be in the path
of the existing groundwater flow or that the remedial technology will intercept
the contaminant plume.
Contaminant fate and transport modeling to illustrate that the chemicals of
concern will not reach the receptors above the risk-based concentrations.
Natural attenuation modeling to evaluate whether the chemicals of concern
will be attenuated by one or more mechanisms before reaching the receptor(s).
Table 2-1: Soil Characteristics That Assist In Treatment Technology Preselection
Treatment Technology Group
Characteristic Physical Chemical Biological Thermal S/S
Particle Size H V V H H
Bulk Density V H
Particle Density H
Permeability H H
Moisture Content V H L L
pH and Eh V V V
Humic Content L L L V L
Total Organic Carbon (TOC) V H H V
Biochemical Oxygen Demand (BOD) H
Chemical Oxygen Demand (COD) H H
Oil and Grease V L L
Organic Contaminants
Halogenated V V L H L
Non-Halogenated V V V H L
Inorganic Contaminants
Volatile Metals V L
Nonvolatile Metals H V L L H
H = higher values support preselection of technology group
L = lower values support preselection of technology group
V = effect is variable among options within a technology group
S/S = Soil Stabilization
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Table 2-2: Water Characteristics That Assist In Treatment Technology Preselection
Treatment Technology Group
Characteristic Physical Chemical Biological Thermal
pH and Eh V V V
Total Organic Carbon (TOC) V H H
Biochemical Oxygen Demand (BOD) H
Chemical Oxygen Demand (COD) H H
Oil and Grease V L
Suspended Solids H L V
Dissolved Solids V H V
Nitrogen and Phosphorus V
Acidity and Alkalinity V V L
Dissolved Oxygen H
Organic Contaminants
Halogenated V V L H
Non-Halogenated V V V H
Metals V H L L
H = higher values support preselection of technology group
L= lower values support preselection of technology group
V = effect is variable among options within a technology group
There are many types of models varying in complexity from analytical models (which are
essentially equations) with minimal data input requirements to comprehensive numerical models
that require as input considerable data about the spatial distributions of aquifer characteristics in
one or more layers.
Before the data collection (investigation) phase is performed, the LRS should determine
model objectives and model type, to justify the data requirement. The data input requirements
and the planned uses of the output from the anticipated model(s) should be listed and discussed
in the SAP, as applicable.
When selecting a fate and transport model, it is critical that site-specific information be
reviewed along with model specifications to ensure that the model is capable of simulating site
conditions and contaminant properties that may have significant impact on site-specific
contaminant transport.
2.3.3.1 Physical Characteristics of Each Water-Bearing Zone
Certain site-specific information should be collected during the investigation phase(s) for
subsequent input into the model(s), which may include, but is not limited to:
Depth to groundwater
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Recharge
Saturated hydraulic conductivity (permeability) or transmissivity
Unsaturated hydraulic conductivity
Aquifer thickness
Groundwater flow direction (including any off-site pumping effects)
Hydraulic gradient (maximum and average)
Groundwater seepage velocity
Dispersivity
Bulk density (saturated zone)
Organic carbon fraction (saturated and unsaturated zones)
Total porosity (saturated and unsaturated zones)
Effective porosity (or specific yield)
Cation exchange capacity
Clay mineral content
2.3.3.2 Chemical Characteristics of the COPCs
In addition to the physical conditions of the site, the chosen model must be able to handle
all contaminant-specific properties that may significantly affect fate and transport. One critical
factor will be whether COPC’s include organic contaminants (such as benzene or
trichloroethene) or inorganic contaminants (such as lead or chromium). The most important
properties affecting organic contaminant transport are compound partition coefficients [such as
the Henry’s Law constant and the organic-carbon partition coefficient (Koc)] and the amount of
organic carbon in the soil. Transport of inorganic contaminants, however, is heavily influenced
by soil properties such as pH, redox potential and clay content (Luckner, 1991; Tyler, 1982;
Korte, 1976). Properties to consider may include:
Horizontal and vertical extent of contamination
Volume of release (or initial concentration near source at time of release)
Solubility
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Acid and base hydrolysis
Oxidation-reduction potential
Valence state of the contaminant
Vapor pressure
Henry’s Law constant
Koc or octanol-water partition coefficient (Kow)
Degradation (daughter) products
Degradation rates of parent and daughter products
Note that it is not necessary for the chosen model to simulate all of the above listed
properties, but only those properties that are relevant to the specific site.
2.4 Developing Specific Investigation Techniques for SAPs
The data requirements, as defined in Section 2.3, will be used to identify appropriate
investigation techniques to be implemented at the site. The data requirements and proposed
investigation techniques will be documented in the SAP. The investigative techniques should be
designed to collect sufficient data for the LRS to refine the conceptual site model until:
Adequate data is available for remedial design and/or
The site risks are determined to be minimal
The following subsections provide guidance for the investigation of various
environmental media. The sampling program should only investigate the media of potential
concern. Therefore, several of the following sections may not be applicable for a given site,
depending on the nature and extent of the contaminants of concern. For example, a former
gasoline station property may not need to be investigated for groundwater contamination if it can
be documented that the residual soil contamination did not extend to the water table during tank
removal operations, and the residual soil contamination was removed.
The use of composite samples must be consistent with the Data Quality Objective and
analytical methods selected. The LRS should balance (1) performing the site investigations in a
phased manner to avoid unnecessary investigations of certain media (e.g., groundwater), and (2)
minimizing the number of phases of investigation by anticipation of applicable data needs for
risk assessment, remedial design and modeling (as applicable) early in the site investigation
process.
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2.4.1 Data Quality Considerations
The data quality objectives (DQOs) for the project should be established prior to
preparation of a SAP. The DQOs are based on the project objectives, key performance
requirements for the data operations and conceptual sampling design. The sampling design and
DQOs are used to develop the SAP, which generally consists of the Quality Assurance Project
Plan (QAPP) and Field Sampling Plan (FSP). The SAP provides detailed site-specific
objectives, specifications, and procedures needed to conduct a successful field investigation.
The SAP specifies the sampling strategies; number, type and location of samples; and the level
of quality control.
The quality of data collected during a field investigation is based on the project DQOs.
Under the West Virginia VRRA, environmental monitoring and measurement efforts must be
validated. WVDEP prefers level III validation although other levels may be discussed with
them on a site by site basis as well as the percentage of samples that will be validated at each
level. The WVDEP must be able to verify that investigative work, risk assessment, confirmatory
sampling and other remediation tasks will be conducted in a manner that will provide reliable
analytical results and an accurate conceptual site model. Examples of quality requirements are
as follows:
analytical reporting limits must be at or below the cleanup criteria
field screening techniques must include proper instrument calibration
sample collection procedures must not impair the sample integrity
Further guidance on quality requirements may be found in the references listed below:
USEPA 1993. EPA Quality System Requirements for Environmental
Programs (Draft) EPA/QA/R-1
USEPA 1993. EPA Requirements for Quality Assurance Project Plans for
Environmental Data Operations (Draft Final) EPA/QA/R-5
USEPA 1993. Guidance for Planning Data Collection in Support of
Environmental Decision-Making Using the Data Quality Process. EPA/QA/G-
4
USEPA 1993. Guidance for Conducting Environmental Data Assessments
(Draft) EPA/QA/G-9
USEPA 1993. Data Quality Objective Process for Superfund-Interim Final
Guidance. EPA 540-R-93-071
USEPA 1998. EPA Guidance for Quality Assurance Project Plans
EPAQA/G-5
2 - 22
The LRS generating data under the VRRA program has the responsibility to implement
procedures to assure that the precision, accuracy, completeness, and representativeness of the
data are known and documented. To ensure that this responsibility is met, each LRS must
prepare a SAP for each project.
Quality assurance/quality control (QA/QC) procedures will be performed in accordance
with applicable professional technical standards, West Virginia requirements, government
regulations and guidelines, and specific project goals. QA/QC procedures are required for both
on site analyses (e.g., field screening, pH, specific conductance) and off site analyses. The level
of the QA/QC shall be based on the project DQOs. Samples collected during VRRA activities
are to be logged on a chain-of-custody form. The following QC samples are generally applicable
to VRRA fieldwork:
Field duplicate samples
Equipment and trip blank samples
Split samples may also be appropriate at the discretion of WVDEP.
At least ten percent of the analytical data or some other percentage agreed to by the
WVDEP must be validated. Standard USEPA protocols for validation (e.g., Contact Laboratory
Protocol or SW-846) should be used. However, these protocols may be modified with the
director’s approval, depending on the type of analyses performed and DQOs. In some cases,
data from previous non-validated investigations may be utilized in the site assessment.
However, new validated data must be generated to substantiate the findings of the earlier studies.
2.4.2 Selection of Analytical Methods
Routine analytical services used for projects under the VRRA should use USEPA or
other approved methods such as those listed in:
USEPA, 1983. Methods of Chemical Analysis for Water and Waste, EPA
600/4-79-020, 1983 rev.
USEPA, 1986. Test Methods for Evaluating Solid Waste, Office of Solid
Waste and Emergency Response, Washington, DC, November 1986 revised
January 1995, SW-846 Third Edition.
Non-standard methods must be approved by the Director.
At a minimum, a description of the analytical method, QA/QC requirements, and
detection limits should be provided for review in all work plans and the Final Report. It would
also be prudent to summarize other analytical requirements such as sample containers, and
preservation techniques for the benefit of the field sampling team. A table showing this
information by media and sample location will facilitate review. All required QA/QC, as
specified in the analytical method, should be implemented during the analysis unless the
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laboratory can demonstrate that modifications to the method provide better results. The QA/QC
information to be reported is based on the DQOs for the parameter.
2.4.3 Health and Safety Considerations
The Occupational Safety and Health Administration’s (OSHA) Hazardous Waste
Operations and Emergency Response (HAZWOPER) standard is applicable to VRRA site
investigations. OSHA has adopted the HAZWOPER standard under its General Industry
Standards (29 CFR 1910.120) and Construction Industry Standards (29 CFR 1926.65). A major
component of this standard that will effect VRRA site investigations is the requirement for
development of a site or project-specific health and safety plan (HASP). The HASP must consist
of the following elements:
Safety and health hazard analysis by task
Employee training requirements (e.g., 40-hour initial training and 8-hour
refreshers)
Personal protective equipment (PPE) requirements by task
Medical surveillance
Air and personnel monitoring
Site control program
Decontamination
Emergency response plan
Confined space entry procedures (if applicable)
Spill containment
The specifics of the elements listed above will vary for each site investigation based upon
the site conditions and the planned activities. Other OSHA regulations, in addition to the
HAZWOPER standard, will need to be addressed, such as: the permissible exposure limits (PEL)
of air contaminants, chemical-specific standards, respiratory protection program, lockout/tagout
procedures, and proper excavation procedures.
2.4.4 Surface and Subsurface Soils
Surface soil and subsurface soil characterizations are primarily performed to obtain
information for determining whether the soil has been impacted (contaminated) due to past
chemical handling activities at the site. Various investigative techniques can be used for
characterizing soil. These techniques include both intrusive techniques such as conventional
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drilling, and non-intrusive techniques such as geophysical methods. Some techniques provide
qualitative data that can be used to first identify an area(s) of concern. Once the areas of concern
are identified, other investigation techniques (e.g., soil borings or test pits) may be necessary to
collect quantitative sample data for characterizing the area.
The chemical analysis of the soil samples provides quantitative data that can be used to
determine what contaminants are in the soil [e.g., metals, polychlorinated biphenyls (PCBs),
solvent constituents, petroleum constituents)] and the horizontal and vertical extent of
contamination. The soil sample data is used to assess risk to human health under current as well
as future exposure scenarios. Potential impacts to groundwater and ecological receptors can also
be assessed using this data.
Physical testing of the soil (e.g., grain size analysis, compaction properties) and
identification of soil types (e.g., clays, sands, loams, fill) can be performed to obtain properties
that may be useful in evaluating various treatment or containment alternatives. The physical
properties of the soil can also be used for determining the fate and transport potential for various
contaminant types.
Surface and subsurface soil characterizations can be conducted in a variety of ways
depending on site conditions, the end use of the data, cost factors, level of quality, and the level
of accuracy required. In general, surface soil is defined as the top 2 feet of soil. The applicant
should be careful not to dilute contaminants confined to the uppermost surface layers by
sampling across too great a depth. This “layer” of soil is sampled primarily to assess human
health impacts via direct exposure to the soil. Surface soil chemical data can also be used to
“locate” the area of contamination and to assess the overall horizontal extent of contamination
once a “hot” area is located. Subsurface soil is defined in the Rule as soil below two-feet in
depth. The soil above the water table is referred to as the vadose zone. Data collected from
subsurface soils can be used to assess the horizontal and vertical extent of contamination, to
evaluate human health risks due to exposure via construction, or to identify “hot” zones that may
serve as a source of groundwater contamination.
The remainder of this section focuses on the specific techniques and their potential
applicability to performing site characterizations. The following references provide general
guidance for characterizing soils:
ASTM. 1987, Standard Guide for Investigating Soil and Rock (D-420-97)
(Vol. 4.08)
ASTM, Site Characterization - Environmental Purposes With Emphasis on
Soil/Rock/Vadose Zone/Groundwater (D-5730)
USEPA. 1991. Subsurface Characterization for Subsurface Remediation.
EPA/625/4-91/026.
USEPA. 1991. Description and Sampling of Contaminated Soils: A Field
Pocket Guide. EPA/625/12-91/002
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USEPA. 1992. Preparation of Soil Sampling Protocol: Techniques and
Strategies NTIS PB-92220532
2.4.4.1 Non-Intrusive Characterization Techniques
There are several remote sensing methods that can be employed for site characterizations.
These techniques include visible photography, infrared photography, and thermal infrared
scanning. In most cases, remote sensing techniques are used to identify changes in land use,
determine groundwater preferential flow pathways, and detecting near surface
leachate/contamination.
Surface geophysical techniques are usually employed in the initial stages of the field
program for locating subsurface anomalies (e.g., drums, debris, and pipelines) or characterizing
the geology or contaminant plumes. The most routinely used techniques include ground
penetrating radar, electromagnetic induction, electrical resistivity, seismic refraction, metal
detection, and magnetometry.
The following guidance documents provide information on remote sensing and surface
geophysical methods, and focus on the usability/limitations of each technique:
USEPA. 1993. Subsurface Characterization and Monitoring Techniques.
EPA/625/R-93/003a.
USEPA. 1984. Geophysical Techniques for Sensing Buried Wastes and
Waste Migration. EPA/600/7-84/064.
USEPA. 1993. Use of Airborne, Surface, and Borehole Geophysical
Techniques at Contaminated Sites: A Reference Guide. EPA/625/R-92/007.
2.4.4.2 Field Screening and Field Analytical Characterization Techniques
Field screening methods provide an indication of the presence or absence of a particular
type of contamination in site media (primarily soil and groundwater) based on a threshold level
for a given technique. Screening methods provide relative concentrations for chemical classes,
but not usually accurate chemical specific concentrations. In most cases, field-screening
techniques are performed during the initial phase of the site characterization to confirm
suspected areas of concern, help locate an area of concern, or identify soil samples that may be
contaminated.
In most cases, field-screening techniques are limited to volatile contamination, although
field screening can also be performed for other suites of compound [e.g., PCBs, polynuclear
aromatic hydrocarbons (PAHs), metals, pesticides]. Field analytical methods include all
chemical analysis methods capable of providing chemical-specific quantitative data in the field.
Field analytical techniques are usually more rapid and less expensive than full-scale laboratory
analyses. The most commonly used field screening and analytical techniques are: headspace
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screening of soil samples, soil gas surveys, field immunoassay test kits and X-Ray Fluorescence
(XRF).
A soil gas survey is designed to characterize subsurface soil (and groundwater)
contamination. Because the technique involves the testing of vapors from the soil, the technique
is primarily suited for characterizing volatile organic compounds such as solvents and some
components of petroleum products. The sampling operation is relatively quick and produces a
small diameter boring (usually only a few feet in depth). The samples may be collected quickly
by vacuum/suction, or through the use of passive absorbent media, that is left in the boring for a
few days. The soil gas samples may be analyzed in the field using a gas chromatograph or
submitted to a qualified laboratory to assess the presence of specific contaminants (e.g., benzene,
toluene, ethylene, xylene, (BTEX), trichloroethene (TCE), tetrachloroethene (PCE)). The results
are usually plotted on isoconcentration maps. By producing the data in a rapid format, field
decisions can be made with respect to delineation of contaminants during the initial phase of
investigation.
Field test kits are used for on-site detection of contaminants. The test kits offer
reasonably accurate results within a relatively short period of time. The tests are analyte-
specific, and sensitive to levels necessary for regulatory compliance. Test systems can be
purchased for characterizing PCBs, total petroleum hydrocarbons (TPH), PAHs,
pentachlorophenol (PCP), trinitrotoluene (TNT) and other chemicals in soil.
The following references provide additional information with respect to field screening
and analytical techniques:
USEPA. 1987. A Compendium of Superfund Field Operations Methods, Part
2. EPA/540/P-87/001 (OSWER Directive 9355.0-14).
USEPA. 1988. Field Screening Methods Catalog: User’s Guide. EPA/540/2-
88/005.
USEPA. 1991. Second International Symposium, Field Screening Methods
for Hazardous Waste and Toxic Chemicals, EPA/600/9-91/028.
2.4.4.3 Intrusive Characterization Techniques
Intrusive characterization techniques are required to obtain surface or subsurface soil
samples. Intrusive characterization techniques primarily include test pitting, drilling, direct push,
and hand held methods.
Test pitting offers the advantage of visually inspecting subsurface features and debris
which may be contained under the ground surface. However, test pitting is limited to a depth of
approximately 15 to 20 feet or until the water table is encountered. Test pitting is performed
using a conventional backhoe.
Subsurface drilling is required to characterize subsurface soil and bedrock conditions, and
to install piezometers and monitoring wells. Subsurface drilling provides precise detail with
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respect to sampling depths and soil/geologic characterization. Drilling methods are selected
based on the following: availability and cost; suitability for the type of geologic conditions at a
site; and potential effects on sample integrity. A wide variety of drilling methods have been
developed based on various needs and site conditions. The hollow-stem auger method is one of
the most commonly used methods for drilling in unconsolidated deposits, whereas air rotary is
widely employed when drilling in consolidated deposits. The following references provide
additional information pertaining to drilling and soil sampling methods:
Aller, Linda, et al. 1989. Handbook of Suggested Practices for the Design
and Installation of Ground-Water Monitoring Wells. National Water Well
Association.
USEPA. 1993. Subsurface Characterization and Monitoring Techniques - A
Desk Reference Guide - Volumes 1 and 2. EPA/625/R-93/003a&b.
ASTM. 1993. Standard Guide for Investigating and Sampling Soil and Rock.
D420-93, (Vol. 4.08).
ASTM. 1991. Guide for Soil Sampling From the Vadose Zone. D4700-91.
(Vol. 4.08).
ASTM. 1993. Draft Standard Guide for the Use of Hollow-Stem Augers for
Geoenvironmental Exploration and Installation of Subsurface Water-Quality
Monitoring Devices. D18.21 Ballot 93-03, April 28, 1993.
ASTM. 1993. Draft Standard Guide for the Use of Direct Rotary Drilling for
Geoenvironmental Exploration and Installation of Subsurface Water-Quality
Monitoring Devices. D18.21 Ballot 93-03, April 28, 1993.
ASTM. 1993. Draft Standard Guide for the Use of Air-Rotary Drilling for
Geoenvironmental Exploration and Installation of Subsurface Water-Quality
Monitoring Devices. D18.21 Ballot 93-03, April 28, 1993.
ASTM. 1995. Standard Practice for Soil Investigation and Sampling by
Auger Borings. D1452-80, (Vol. 4.08) - Reapproved 1995.
ASTM. 1993 Practice for Diamond Core Drilling for Site Investigation D-
2113-83 (Vol. 4.08)- Reapproved 1993.
ASTM. 1983. Standard Practice for Thin-Walled Tube Sampling of Soils.
D1587-94, (Vol. 4.08).
ASTM. 1992. Method for Penetration Test and Split-barrel Sampling of Soils
D-1586 -84 (Vol. 4.08) - Reapproved 1992.
Direct push technology (such as cone penetrometers, GeoprobeR, and other trade names)
is used to collect lithologic data and/or soil samples for chemical analyses. The advantage of
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direct push technology is that it takes less time than conventional drilling and is less expensive.
In addition, this technique results in less investigation-derived waste (IDW). The disadvantage
of the direct push technology is that it cannot penetrate rock or difficult geologic conditions and
is limited in depth relative to other drilling methods. The following references provide
additional information on the use of this sampling technique:
ASTM. 1986. Standard Test Method for Deep, Quasi-Static, Cone and
Friction-Cone Penetration Tests of Soil. D3441-86. (Vol. 4.08).
Christy, T.M. and S.C. Spradlin. 1992. The Use of Small Diameter Probing
Equipment for Contaminated Site Investigations. Groundwater Management
11:87-101 (6th NOAC).
Chiang, C.Y. et al., Characterization of Groundwater and Soil Conditions by
Cone Penetrometry. In: Proceedings (6th) National Water Works Association
(NWWA)/American Petroleum Institute (API) Conference, Dublin, Ohio. pp.
175-189.
Hand-held sampling techniques include the use of scoops, shovels, and augers. Scoops
and shovels are used in cases where the purpose of the sampling is to obtain surface soil samples
(top 6 to 12 inches only). Hand or power augering is quick and less expensive than the other
methods, but the technique is limited to the depth in which samples can be collected and
geologic conditions. Normally, sampling to shallow depths such as one to two feet can be
accomplished via hand augering. With the use of a power auger, the depth will be greater.
Surface and shallow subsurface soil sampling is usually performed via hand or power augering.
Additional information can be obtained from the following references:
USEPA. 1987. A Compendium of Superfund Field Operations Methods, Part
2. EPA/540/P-87/001 (OSWER Directive 9355.0-14).
USEPA. 1991. Description and Sampling of Contaminated Soils: A Field
Pocket Guide. EPA/625/12-91/002.
2.4.5 Storm Water Runoff
Storm water runoff may be a potential contaminant transport mechanism on some VRRA
sites. Contaminated soils, contaminated trenches or drainage swales, storm sewers or other
conveyance structures may leach contaminants into storm water that may cause an expansion of
the contaminated area of concern and/or contribute contaminants to a surface water body.
Structures, depressions or ditches may have been used to convey process water when the
property was in active use. Although process waters may no longer be conveyed through
drainage avenues, remnant contamination from those historical operations may be present and
may be leaching back into the storm water. Therefore, it may be appropriate to sample storm
water that passes through potentially contaminated areas.
As a result of the National Pollutant Discharge Elimination System (NPDES) which was
authorized by the Clean Water Act (CWA), many industrial facilities were required to prepare
2 - 29
and implement a storm water pollution prevention plan by October 1, 1993. West Virginia is an
NPDES-delegated state and therefore, administers this federal program within the state. A
review of existing information on file at the WVDEP under this program could eliminate the
need for sampling or for identifying potential contaminants of concern with respect to storm
water or process water drainage systems.
Typical storm water sampling under NPDES generally includes eight pollutant
parameters: oil and grease, biological oxygen demand (BOD), chemical oxygen demand (COD),
total suspended solids (TSS), nitrate, nitrite nitrogen, kjeldahl nitrogen, total phosphorus, pH,
and specific pollutants of concern at the site. These parameters may be appropriate to include for
sites where the future land use would likely require an NPDES permit.
Sampling protocol for storm water generally requires that:
sampling begins at a predetermined 0.1-inch of rainfall, with 72 hours of dry
time having elapsed from the time of the last 0.1-inch storm event.
a grab sample be taken within 30 minutes of the onset of a storm event.
composite sampling be conducted for 3 hours or the duration of the storm
event.
The logistics of meeting these protocols may be problematic on abandoned sites where no
personnel are available for timely mobilization. Therefore, it may be necessary to modify these
protocols to match the site data requirements versus the logistical realities of the investigation.
Composite samples can be either flow-weighted or time-weighted. If the applicant is
conducting flow-weighted composite sampling, then, the storm water discharge flow should be
estimated each time a sample aliquot is collected. Common flow measurement techniques
include weirs and flumes, velocity methods, volumetric methods, slope and depth methods, and
runoff coefficient methods.
Sampling can be conducted either manually or with an automated monitoring system.
There are many benefits to using an automated monitoring system including: enhanced safety,
more accurate documentation of the storm event, enhanced data quality and reduced field man-
hours. However, this approach may not be appropriate for preliminary evaluation of storm water
runoff. It may be more appropriate to coordinate the storm water sampling with other site
investigation activities.
The following documents are available to assist the LRS with design of a storm water-
sampling program:
USEPA. 1992. Storm Water Management for Industrial Activities (EPA 832-
R-92-006).
USEPA. 1992. NPDES Storm Water Sampling Guidance Document (EPA
833-B-92-001).
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2.4.6 Site Infiltration and Vadose Zone Characteristics
Contaminants released on the land surface might travel (infiltrate) to the shallow
subsurface above the water table (the vadose zone) and descend (percolate) to the water table.
The relative rates of infiltration and percolation can provide an indication of the likelihood
whether or not contaminants could descend to the groundwater. Additionally, contaminated soils
themselves could become secondary sources of groundwater contamination.
Where soils are found to be contaminated, the information derived from the site
investigations of infiltration and permeability rates would contribute to the feasibility evaluation
or remedial design of soil washing, vapor extraction systems, and other remedial technologies.
The initial qualitative evaluation of vadose conditions can occur during a site
reconnaissance (Section 2.2.2), although the reconnaissance should be supplemented by review
of soil surveys (USDA - Soil Conservation Service [SCS]), the relevant County Report by the
State Geological Survey; other similar sources of information on infiltration, percolation and
recharge potentials; or site-specific information.
Should further site investigations become advisable, field tests of infiltration rate should
be scheduled during other site activities, such as well sampling or drilling activities. Other tests,
such as soil-moisture tension (lysimetry) or isotherm quantification (calculating the rates of
adsorption and remobilization of a particular chemical by the site soils), should only be
scheduled if warranted by the requirements of the risk assessment or remedial design.
The appropriate field methods for permeability testing of the vadose zone, either at land-
surface or in a borehole, are found in the ASTM and USDA-SCS references. Methods for
laboratory testing of consolidated and unconsolidated materials should follow the appropriate
ASTM method. The following provides references for some of the field methods that may be
selected for this investigation:
ASTM. 1990. Test Method for Measurement of Hydraulic Conductivity of
Saturated Porous Materials Using a Flexible Wall Permemeter. D-5084-90
(Vol. 04.09).
ASTM. 1991. Guide for Soil Sampling from the Vadose Zone. D4700-91
(Vol. 4.08).
ASTM. 1994. Practice for Thin-Walled Tube Sampling of Soils. D1587-94,
(Vol. 4.08).
ASTM. 1994. Test Method for Infiltration Rate of Soils (in Field) Using
Double Ring Infiltrometer. D-3385-94 (Vol. 04.08).
2.4.7 Groundwater
Groundwater characterizations are performed when there is a potential for
leaching/percolation of contaminants through the site soils into the uppermost water-bearing
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zone (and potentially into deeper zones). The primary objective of a groundwater investigation
is to determine whether the concentrations of COPCs exceed regulatory limits as specified under
West Virginia’s Requirements Governing Groundwater Standards (Legislative Rule 46CSR12)
or other risk-based standards. A second objective of the groundwater investigation is to
determine the vertical and horizontal extent and magnitude of COPCs and the potential threat to
human and ecological receptors. A third objective of the groundwater characterization is to
evaluate and quantify site hydrogeologic conditions that will govern the COPC fate and
transport. Groundwater investigations are particularly important if the water-bearing zone is an
aquifer or is hydraulically connected to an aquifer that is used as a source of drinking water.
Groundwater characterization may not need to be performed during the initial phases of
investigation if it is considered an unlikely media of concern. For example, groundwater may
not need to be investigated if only surface soils are contaminated and the uppermost aquifer is
known to be deep (e.g., 100 feet) and subsurface soils consisting of clays and silts. However, a
groundwater investigation (that was initially considered unnecessary) will need to be conducted
during later phases of investigation if soil sampling indicates that the initial conceptual model
was in error, and that significant contaminant leaching/percolation has occurred.
Data generated for groundwater characterizations may be collected during a single or
over several phases. An example-phased investigation could be as follows:
1. Installation of temporary or permanent groundwater sampling points (e.g.,
temporary direct push borings, well points, monitoring wells, extraction wells)
2. Collection of groundwater samples to determine the presence/absence of the
COPCs.
3. Collection of data necessary for estimation of groundwater flow rate and
transport mechanisms (e.g., groundwater elevation data, porosity estimates,
hydraulic conductivity estimates, definition of aquifer boundaries)
4. Installation of additional wells and collection of additional samples, to
determine the extent of a plume, to better evaluate remedial alternatives, or for
groundwater model calibration.
In addition to the standard investigation techniques, other investigation techniques may
be employed to collect groundwater data (e.g., surface geophysics, borehole geophysics, soil gas
surveys, remote sensing, tracers).
Factors that would impact the level of effort for completion of the groundwater
characterization may include the following:
1. Concentrations of the identified COPCs relative to the risk based standards
2. Presence of non-aqueous phase liquids (NAPLs)
3. Complexity of site hydrogeologic conditions (e.g., non-stratified vs. stratified
(alluvium, colluvium, fractured bedrock, fill material)
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4. Point source vs. non-point source release mechanism for the COPC
5. Chemical properties of the COPC (e.g., solubility, KOC, density, vapor
pressure)
6. Attenuation processes
7. Location of human and ecological receptors
8. On-site and off-site wells
9. Facility structures and utilities (e.g., preferential migration pathways)
10. Other site-specific factors
2.4.7.1 Well Installation and Groundwater Quality Investigation
Groundwater sampling points can be established using a variety of temporary or
permanent wells (such as, temporary wells installed via direct push technologies, well points,
monitoring wells, extraction wells). Additionally, springs and seeps may be used as sampling
points, since they typically represent zones of preferred groundwater migration. The number of
sampling points necessary to adequately characterize a site is to be based on the site-specific
characteristics.
Monitoring wells must be designed and installed in accordance with West Virginia’s
regulatory requirements as defined in the Monitoring Well Regulations (47CSR59) and the
Monitoring Well Design Standards (47CSR60). The regulatory framework allows the LRS to
make a selection of the specific drilling technologies and well materials to be utilized.
Note: Monitoring wells with turbid samples may not provide reliable analytical results for
metals.
Selection of appropriate drilling techniques, well installation techniques, well materials,
well diameter, and sampling techniques are dependent on a wide variety of site specific geologic
and hydrogeologic factors as well as the characteristics of the COPC. Some of those factors
could include:
Purpose of the well (e.g., piezometer, chemical sampling, groundwater
extraction, geophysical logging)
Anticipated depth to groundwater
Single versus multiple water bearing zones
Physical characteristics of the site soils and/or bedrock (e.g., density, tendency
to heave, formation permeability)
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Chemical characteristics of the site soils (e.g., will soils be hazardous?)
Chemical characteristics of the site groundwater (e.g. will groundwater be
corrosive to well materials?)
Logistical constraints (e.g., location of property boundaries, steep slopes,
overhead power lines)
Other site specific characteristics
The characterization of groundwater quality and site hydraulic characteristics must be
directly relevant to the COPCs found on site and must directly support the remediation standards,
remedial design, and/or groundwater model. The characterization of groundwater quality should
provide useful quantification of the concentrations of COPCs at individual monitoring points
across the site. Laboratory methods for analysis should be selected to conform with the DQOs
(Section 2.4.1 and 2.4.2) and other pertinent regulatory requirements. Consistent with the West
Virginia Requirements Governing Groundwater Standards (Legislative Rule 46CSR12),
compliance with risk-based concentrations for inorganic parameters will be based on dissolved
phase concentrations rather than total concentrations.
Useful resources to assist the LRS in development of the groundwater quality
investigation program include:
Aller, Linda, et al. 1989. Handbook of Suggested Practices for the Design
and Installation of Ground-Water Monitoring Wells. National Water Well
Association.
Driscoll, F.G. 1986. Groundwater and Wells; 2nd
Ed.; Johnson Filtration
Systems, Inc.; Minnesota.
USEPA. 1993. Subsurface Characterization and Monitoring Techniques - A
Desk Reference Guide - Volumes 1 and 2. EPA/625/R-93/003a & b.
USEPA. 1987. Handbook - Groundwater. EPA/625/6-87/016
USEPA. 1991. Handbook - Ground Water Volume II - Methodology.
EPA/625/6-90/016
2.4.7.2 Characterization of Groundwater Flow
The objective of the hydrogeologic characterization is to provide a quantification of the
ability of the water-bearing unit at the site to transmit water and transport contaminants to a
potential receptor. The level of detail required for evaluation of the site hydrogeological
investigation will vary depending on the data requirements for risk assessment, remedial design
and/or modeling. The characterization of groundwater flow usually proceeds from the simplest
method to more complex methods. Listed below are some of the techniques available to the LRS
for quantifying the site-specific hydrologic properties.
2 - 34
The usual methods of hydrologic characterization are:
Potentiometric Surface-Mapping
A potentiometric surface map (e.g., groundwater contour map) is used to evaluate the
direction of groundwater flow. Also, gradient calculations can be made from this
map using either flow-net, flow-line or three-point calculations.
Hydraulic Conductivity and Porosity Evaluation Techniques
Several methods are available to the LRS to estimate the hydraulic conductivity of the
subsurface stratigraphic profile. Specific examples include:
- Literature Review of Hydrogeologic Parameters Values (e.g., porosity, hydraulic
conductivity):
The least reliable estimation of hydraulic conductivity, is available from standard
references (such as Freeze and Cherry, 1979, p29; Driscol, 1986, p75). This
estimation can be made from a visual estimate of grain-size or rock type, or from
laboratory distribution analysis of the grain-size (ASTM D 421 and 422). As an
indication of the probable ability of the subsurface at the investigation site to transmit
groundwater, this estimation is suitable only for preliminary planning.
- Grain-Size Distribution:
The calculation of hydraulic conductivity from grain-size distribution (such as Freeze
and Cherry, 1979, p350-351; Driscol, 1986, p 738) is more reliable than estimation
from literature values. The most relevant application for this calculation is in the
sizing of well-screens and filter pack for proper well design and installation.
Expansive use of these specific calculations to characterize the site-specific hydraulic
conductivity is not typically adequate for making remedial design decisions; however,
such estimates can be useful for planning.
- Laboratory Tests (Triaxial Chamber Tests - Vertical Permeability):
Laboratory tests of vertical hydraulic conductivity [ASTM D-5084] are useful
indicators of the probable rate of vertical percolation of groundwater through the
vadose zone; water-bearing zone, and/or aquitards. The calculations from these tests
are more reliable than those of the grain-size distribution, but are generally limited to
the assessment of vertical hydraulic conductivity.
- Time Lag Permeability Tests (Slug Tests)
Time lag permeability tests [ASTM Method D-4044, or other applicable guidance
references (Hvorslev, 1951; Bouwer and Rice, 1976)] are single-point calculations of
hydraulic conductivity based on the rate of recovery in response to an instantaneous
change in the water level in the well. It is recommended that the tests be performed at
multiple locations, as applicable, to evaluate the hydraulic variability across the site.
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The results are more commonly used to find a likely average hydraulic conductivity
of the site.
Aquifer Tests (Pump Tests)
Aquifer testing (ASTM Method D-4050 or other applicable guidance) is the most
reliable technique for calculating the hydraulic properties of the water bearing zone(s)
underlying a site. Data collected from a properly designed aquifer test may provide
quantitative and qualitative information such as:
- Quantitative
Hydraulic properties: (e.g., transmissivity, hydraulic conductivity, specific
capacity, specific yield)
Zone of influence (if steady state conditions are achieved)
Sustainable yield (if steady state conditions are achieved)
- Qualitative
Aquifer type (e.g., confined, unconfined, leaky confined)
Borehole storage, well efficiency
Zone of influence (transient conditions)
Heterogeneity/anisotropy
Connectivity between multiple layers (as applicable)
The results of the aquifer tests can assist in defining modeling input parameters and
remedial design criteria.
Tracer Tests
Tracers are used as an effective means to evaluate the site hydraulic characteristics.
The tracers can include dyes, salts, or trace elements. The tracer may be introduced
into on-site groundwater (via monitoring wells, etc.). The presence of the tracer is
monitored at designated points including extraction wells, springs/seeps, and other
monitoring points. Tracer data are used to evaluate groundwater flow pathway, flow
velocities, and other contaminant transport properties of the water-bearing zone (e.g.
dispersion).
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Modeling
Although modeling may be done by a variety of means, modeling by computer is the
most common. Computer models are to be performed by qualified individuals and
are highly dependent on the quality of available data. Selection of the most
appropriate model must be carefully considered by a qualified professional to best
suit the amount of available data and to achieve the modeling objectives (i.e., future
COPC fate and transport patterns, remedial design). [See Section 2.4.12].
The following lists indicate some of the standard sources of information useful in
designing and characterization of hydrogeologic parameters.
Driscoll, F.G. 1986 Groundwater and Wells. 2nd
Ed. 1986. Johnson Filtration
Systems, Inc. Minnesota. Chr.16.
Freeze, R.A. and Cherry, J.A. 1979. Groundwater. Prentice-Hall.
Kruseman, G.P. and deRiddler, N.A. 1991. Analysis and Evaluation of
Pumping Test Data. 2nd
Ed. ILRI Publication 47. The Netherlands.
Lohman, S.W. 1972. Ground-Water Hydraulics. USGS-Prof. Paper 708.
USGPO.
Fetter, C.W., 1994. Applied Hydrogeology, 3rd Edition.
Fetter, C.W., 1993. Contaminant Hydrogeology.
2.4.8 Surface Water and Sediment Sampling
Surface water and sediment sampling may be necessary if there is a possibility that
contamination from the site at concentrations above risk-based levels could potentially migrate to
a nearby surface water body (e.g., stream, spring, lake). The objective of the sampling will be to
determine if the site has caused conditions that would pose an unacceptable risk to human-health,
the environment and/or if applicable regulatory criteria have been exceeded as defined by 46
CSR 1.
Surface water bodies may have become contaminated as a result of spills, routine
permitted or historical discharges, runoff from contaminated area(s), groundwater discharge or
other routes. Selection of sampling locations should be based on the conceptual site model and
anticipated contaminant transport mechanisms. In general, surface water samples should be
collected in accordance with the instructions given in Appendix J. Sediment samples should be
located at (and downstream of) the predicted locations where contaminants have entered and/or
are entering the water body. The number of samples should be sufficient to characterize the
extent of any potential contamination and to provide a sufficient database for risk assessments, if
necessary. Samples also should be collected from upstream locations, and non-impacted
“background” stations, if possible.
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It is important to identify the final uses of the data prior to sample collection so all of the
necessary data can be collected to evaluate risk or remedial design options. For example,
parameters such as pH, hardness, total organic carbon (TOC), grain size, dissolved and/or total
metals, Simultaneously Extracted Metals (SEM), Acid Volatile Sulfides (AVS) and pore water
concentrations may be necessary to evaluate ecological risks in addition to chemical tests for the
COPCs. The analytical laboratory should be contacted to discuss appropriate analytical
detection limits, since evaluation criteria for ecological receptors may require the use of
detection levels lower than those routinely specified by a particular method.
The following reference manuals provide guidance for design of a sampling program, as
well as a description of various sampling techniques:
USEPA. 1992. Guidance for Performing Site Inspections under CERCLA,
Interim Final. USEPA, Hazardous Site Evaluation Division, Office of Solid
Waste and Emergency Response, EPA/540-R-92-021. September 1992.
USEPA. 1988. Guidance for Performing Remedial Investigations and
Feasibility Studies under CERCLA, Interim Final. USEPA, Hazardous Site
Evaluation Division, Office of Solid Waste and Emergency Response,
EPA/540/G-89/004. October 1988.
USEPA. 1992. NPDES Storm Water Sampling Guidance Document.
USEPA, Office of Water, EPA/833-B-92-001. July 1992.
NJDEP. 1992. Field Sampling Procedure Manual. New Jersey Department
of Environmental Protection and Energy. May 1992.
USEPA. 1991. Compendium of ERT Surface Water and Sediment Sampling
Procedures, Surface Water Sampling SOP #2013, EPA/540/P-91-005,
OSWER Directive 9360.4-03.
2.4.8.1 Surface Water
When evaluating risk or treatment alternatives with regard to surface, both contaminant
and receiving stream characteristics must be considered. This may include examining maximum
contaminant concentrations for evaluating acute impacts or average concentrations for
determining exposures. The receptors, whether human or ecological, will have different
exposure times and routes which must be taken into account. Also, worst case scenarios may
need to be included in the analysis. For example, a small stream receiving contaminated
groundwater recharge should tend to have higher concentrations during periods of low flow than
after precipitation events (which may dilute the water samples). On the other hand, if the
contamination is coming from surface water runoff, then the samples collected during periods of
heavy rainfall may be representative of worst-case concentrations.
In addition to chemical data, flow velocity and/or discharge measurements will be
necessary if it is important to estimate the mass of contamination that is entering the water body.
Discharge measurements for streams can typically be made by measurements of flow velocity
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and discharge area. Procedures for measurement of discharge rates can be found in most
hydrology textbooks or USGS publications.
Surface water samples can be collected from different depths (e.g. surface, vertical mid-
point, near bottom, composites, etc.) as appropriate for anticipated exposure scenarios. There are
several types of sampling equipment and sampling techniques that can be used to collect water
samples. The New Jersey Field Sampling Procedure Manual (NJDEP, 1992) contains a thorough
description of sampling techniques/equipment, along with advantages and disadvantages of each.
A few of the more common sampling techniques/equipment are as follows:
Direct Dip
Weighted Bottle Sampler
Wheaton Dip Sampler
Kemmerer Depth Sampler
Beacon Bomb Sampler
PACS Grab Sampler
Pump
2.4.8.2 Sediment
Sediment sampling may be appropriate when:
Contaminant properties suggest they may be present in only trace levels in the
water column, but could accumulate to high concentrations in sediments;
Sediments may act as a reservoir and source of contaminants to the water
column;
Sediments may accumulate contaminants over time, while contaminant levels
in water are more variable; or
Sediment contaminant levels could affect benthic organisms or other receptors
of concern in aquatic ecosystems.
The sediment samples can be collected near the surface or at depth, as appropriate.
However, risk evaluations generally are more concerned with the surficial sediments than deeper
ones. There are several types of sampling equipment and sampling techniques that can be used
to collect sediment samples. A few of the more common sampling techniques/equipment are as
follows:
Thin Wall Tube Auger
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Scoop/Trowel
Sediment Corer
Gravity Corer
Bucket Auger
Ponar Dredge
Eckman Dredge
PACS Sludge Getter
Sludge Judge
In general, sampling equipment which minimizes or eliminates the loss of fine-grained
material is preferred over such equipment as scoops/trowels, which tend to result in the loss of
fine-grained material and therefore do not provide sediment samples that are representative of
conditions to which biota would actually be exposed.
The New Jersey Field Sampling Procedure Manual (NJDEP, 1992 Compendium of ERT
Surface Water and Sediment Sampling Procedures, Sediment Sampling SOP# 2016 (USEPA,
1991) contain thorough descriptions of sampling techniques/equipment, along with advantages
and disadvantages of each and should be consulted for additional information.
2.4.9 Indoor Air Quality (IAQ)
IAQ may be a concern on some VRRA sites, where the property development
alternatives include reuse of existing buildings or construction of new buildings in areas of
known or suspected contamination (e.g., volatile organics, etc.). In areas where existing
buildings will be reused, an assessment of IAQ may sometimes be warranted. Modeling of
future IAQ for new structures is difficult. However, engineering controls (e.g., vapor stop,
subsurface ventilation, building structures without basement) can be incorporated into building
designs to reduce the potential for future IAQ problems associated with buildings planned for
areas with elevated radon and/or volatile organic compounds (VOC) containing soils.
IAQ is a complex occupational health issue. Building owners and occupants are
concerned with low level exposure resulting from surrounding soil and groundwater
contamination, outdoor air pollutants, contaminants present or generated from building materials
or occupants, and biological agents such as bacteria and fungal spores. Generally, sick building
syndrome can be caused by many factors including work environment, airborne contaminants
and psychological issues.
The components of an IAQ assessment may include: (1) an evaluation of the building's
ventilation system, (2) identifying sources of pollution from the surrounding area, (3) an
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inspection of the facility for sources of indoor air pollution, and (4) precise instrumentation and
proper analytical methods to measure factors affecting the air quality in the building. These
components may include (but are not limited to) the following:
VOCs
Radon
Temperature and Humidity
Air movement / velocity
Carbon dioxide
Carbon monoxide
Formaldehyde
Ozone
Micro-organisms (for example, fungus, bacteria)
While all of the parameters may be a concern in a real estate transaction, this section of
the document focuses on those issues that present a concern primarily due to the condition of the
land (e.g., radon and VOCs), as opposed to those resulting from the condition or management of
the structure(s).
2.4.9.1 Volatile Organic Compounds
Hundreds of VOCs are found in indoor air at trace levels. VOCs may present an IAQ
problem when individual organics or mixtures exceed normal background concentrations. The
presence of VOCs may be due to many sources including: (1) those within the building
(chemicals off-gassing from carpets, furniture and construction materials), and (2) contaminated
soils or groundwater surrounding the structure(s). When investigating the presence and sources
of VOCs within the indoor air of a building, careful examination of these conditions should be
conducted.
Several direct-reading instruments are available that provide a low sensitivity "total"
reading for different types of organics. Such estimates are usually presented in parts per million
and are calculated with the assumption that all chemicals detected are the same as the one used to
calibrate the instrument. A photoionization detector or flame ionization detector is an example of
a direct-reading instrument used as a screening tool for measuring total VOCs (TVOCs). Direct-
reading instruments do not provide sufficient sensitivity to differentiate normal from problematic
mixtures of organics. However, instantaneous readouts may help to identify "hot spots," sources
and pathways and can identify peak exposures if they happen to occur during the measurement
period.
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In addition to direct reading instruments, laboratory analyses of an air sample collection
media (e.g., sorbent tubes, collection filters, and canisters) can provide an estimate of TVOCs in
the air or the concentration of specific compounds. Generally, TVOCs or compound-specific
concentrations determined by air sample collection and analysis provide more accurate results,
but are unable to distinguish peak exposures.
High concentrations of individual VOCs may also cause IAQ problems. Individual VOCs
can be measured in indoor air with varying degrees of sensitivity (i.e., measurement in parts per
million to parts per billion) depending on the air sampling methodology used. Examples of
collection media utilized by the sampling methodologies include sorbent tubes and evacuated
canisters. Analysis involves gas chromatography followed by mass spectrometry.
Occupational exposure standards exist for many VOCs. No safety factors for applying
these occupational limits to general IAQ are currently endorsed by USEPA and the National
Institute for Occupational Safety and Health (NIOSH). Guidelines for public health exposure (as
opposed to occupational exposure) for a few VOCs are available in the World Health
Organization (WHO) Air Quality Guidelines for Europe. The Pan American Health Organization
in Washington, D.C. is the regional office of the WHO for the United States (202) 974-3000.
The WHO can also be accessed on the Internet at www.who.org. These guidelines address non-
carcinogenic and carcinogenic effects. Measurement of trace organics may identify the presence
of VOCs whose significance is difficult to determine. It may be helpful to compare levels in
complaint areas to levels in outdoor air or non-complaint areas.
2.4.10 Tanks, Drums and Asbestos Containing Materials (ACM)
2.4.10.1 Tanks and Drums
Industrial and commercial operations often rely upon tanks, vessels, or drums for the
storage of raw materials, product, or waste. These units generally consist of above or below
grade tanks (buried or vaulted), process vessels (including reaction vessels, mixing or blending
tanks) and barrels (commonly 55 gallon steel or fiberboard drums). Related pumps, piping or
drains also may be present, and may contain residues similar to that found within the tanks or
vessels.
As part of a VRRA assessment of a former industrial or commercial facility, the location
of, and assessment, of existing tanks, vessels, or drums are critical; given the short and long-term
hazards which may now be associated with these units. The actual hazard(s) can vary greatly,
and is largely dependent upon: (1) the materials previously stored within the units; (2) the
condition of the units at the time operations ceased; and, (3) conditions affecting the units while
idle (e.g. product deterioration).
Collecting the information necessary to assess and document current conditions consist of
a number of inter-related tasks. The need for, extent and complexity of subsequent tasks is
largely dependent upon the findings of the initial document review, and, as necessary, sampling
of the contents of the units (to confirm documented conditions or gather baseline information
when no information exists).
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Two tasks necessary for the evaluation of a site include a document search of existing
information and field verification of those conditions. This search could include both facility
and public documents and would focus on process descriptions as well as chemical usage. This
information, conducted prior to field investigation/verification would be used to:
1. Aid in the planning and development of a site-specific health and safety plan
(e.g., HASP). Specifically, the information would be used to identify known
chemical hazards (e.g. potential for explosive vapors to be present within
sealed containers) as well as physical hazards which may be present (i.e.
piping or vessels requiring destructive/confined space entries for inspection);
2. Provide background information for sampling purposes. Specifically, the
information may be used for sample groupings of compatible materials as well
as the segregation of unique (non-compatible materials). For instance, metal
plating operations commonly utilize both acid and cyanide bearing solutions
within the various plating baths (and within the same area). Mixing of these
incompatible waste streams during sampling could have significant detrimental
effect on site workers.
3. Assist in the identification of waste classification (for subsequent remedial
purposes, as necessary); and
The second necessary task includes field verification of the background conditions.
Based upon the complexity of the site, the field effort may include the following:
1. Confirmation of existing (remaining) tanks, vessels, or drums, including
ancillary piping;
2. Visual inspection of the tanks vessels or drums, noting their current physical
condition, contents and any other pertinent features (e.g., labels, pressure
buildup); and,
3. Obtaining representative samples, as necessary.
At a number of old sites, incomplete or inaccurate records exist. Accordingly, the field
investigation also is intended to locate and identify previously undocumented tank or drum
staging areas. Some of these undocumented tanks could be associated with manufacturing
support operations, such as maintenance, power distribution, or on-site waste treatment areas. In
these instances, the items/chemicals of concern often include chemicals not associated with the
manufactured product, but rather support operations and include hydraulic oils, fuels,
refrigerants, etc. These areas could be dispersed throughout a facility. Accordingly, buried tanks
or vessels abandoned in-place (where surface structures such as vents and dispensing stations
have been removed) may not be readily apparent today without the use of subsurface geophysical
equipment.
Given the wide and unique conditions possible within individual sites, which may be
encountered, a comprehensive description of site inspection/sampling protocols is not included in
this guidance. However, prior to any site activities, development of a site-specific Health and
Safety/Sampling Plan is required. This Plan, developed in accordance with OSHA 1910
2 - 43
regulations would establish project health and safety protocols consistent with necessary
sampling objectives. For tanks, vessels, and drums, these plans commonly include:
1. Mandatory use of personnel protective equipment for use with flammable,
reactive, corrosive, shock sensitive or toxic chemicals;
2. Confined Space entry procedures (to gain entry for inspection/sampling
purposes);
3. Hot Work Permits (for cutting and welding, when permissible); and,
4. Line-breaking procedures for opening pipelines of unknown condition.
2.4.10.2 Asbestos Containing Materials
Over the years, many building materials were made with asbestos. Materials commonly
recognized as potential asbestos containing materials (ACMs) consist of thermal pipe insulation
and spray-on fire proofing. Other materials may contain asbestos, such as flooring products,
roofing materials, joint compound, plaster, ceiling products, wire insulation, and more. The
USEPA, OSHA, state, and many local environmental and health and safety agencies have
developed regulations governing the management of asbestos. These regulations may have an
impact on some site investigations.
The USEPA’s Asbestos National Emission Standards for Hazardous Air Pollutants
(NESHAP) regulation is intended to minimize the release of asbestos fibers during activities that
involve the handling or disturbance of ACM. The NESHAP regulation requires notification of
the applicable regulatory authority prior to the demolition of any building/structure, or prior to
renovation activities that will disturb ACM in the amount prescribed by either federal, state, or
local regulations. In addition, OSHA’s asbestos standards require the identification of ACM to
protect workers during activities that may disturb ACM. In nearly all cases, compliance with
these regulations will require an asbestos survey at VRRA sites that include the presence of
buildings/structures.
Most states and some local regulatory agencies require asbestos surveys to be performed
by trained and licensed individuals. The asbestos survey conducted by the qualified individual
should consist of the following items at a minimum:
Location and description of identified potential ACM
Assessment of the friability of the material
Condition assessment
Collection of an appropriate number of bulk samples of the material based on
the quantity
Analysis by a laboratory accredited for bulk asbestos fiber analysis by the
National Institute of Standards and Technology under the National Voluntary
Laboratory Accreditation Program (NIST/NVLAP)
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Quantity of the ACM
2.4.11 Decontamination
This section provides guidance regarding decontamination of field equipment including
sampling devices as well as heavy equipment such as back hoes and drill rigs. Decontamination
procedures will be an integral part of most if not all SAPs.
Decontamination is the process of removing or neutralizing contaminants which may
have accumulated on field equipment. This process provides for protection of personnel, reduces
or minimizes the transfer of contaminants between sampling locations (i.e., cross-contamination)
or from contaminated zones to non-contaminated zones. Decontamination procedures are
developed during the project planning stage (i.e., development of SAP).
The LRS is responsible for ensuring that the proper decontamination procedures are
identified in the SAP. The field team leader is responsible for ensuring that the field
decontamination procedures are implemented properly in the field.
The following references include information about decontamination alternatives.
ASTM. 1990. Standard Practice for Decontamination of Field Equipment
Used at Nonradioactive Waste Sites. D5088-90, (Vol. 4.08), ASTM,
Philadelphia, PA.
USEPA. 1985. Guide to Decontaminating Buildings, Structures, and
Equipment at Superfund Sites. EPA/600/2-85/028.
USEPA. 1992. RCRA Groundwater Monitoring Technical Enforcement
Guidance Document (TEGD). Office of Waste Program Enforcement.
OSWER Directive 9950.1.
2.4.11.1 Heavy Equipment
All heavy equipment such as drill rigs, back hoes, augers, and down hole tools should be
decontaminated prior to drilling, excavation, or sampling activities are performed. “Dirty”
equipment may result in false positive sampling results simply due to contamination from
another site. Therefore, prior to performing any field activities, or prior to leaving the “hot zone”
at the site, heavy equipment should be decontaminated. For augers and other down hole tools,
decontamination should be performed between each sampling location.
Typically, decontamination of heavy equipment involves high-pressure water and/or
steam cleaning. When necessary, the equipment can be cleaned with a scrub brush and soap-
water solution prior to steam cleaning in order to remove visible signs of contamination (e.g.,
petroleum, oils, or tars).
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Decontamination of heavy equipment will frequently be conducted in a designated area
and over a pre-constructed decontamination pad, when containerization of the decontamination
fluids is deemed appropriate. However, in some instances, decontamination may be conducted at
the point where the heavy equipment was used, if such a procedure does not cause conditions to
become more hazardous than they already are and/or create surficial concentration of
contaminants in excess of risk-based concentrations.
A decontamination pad can be a lined pit or concrete/asphalt pad that is designed to
accumulate the decontamination fluids. The objective of the decontamination pad is to collect the
fluids without discharging to the ground surface, and to retrieve the fluids into a centralized
location.
2.4.11.2 Sampling and Field Equipment
To better ensure that the chemical analyses represent actual field conditions, sampling
equipment should be properly decontaminated prior to the field effort, during the sampling
program (i.e., between sample locations or sample intervals), and at the conclusion of the field
program. Preferably, dedicated sampling equipment (e.g., bailers) or disposable sampling
equipment should be employed.
Soil, sediment, and water sampling equipment typically includes, but is not limited to, the
following: split-barrel samplers (split-spoon samplers), bailers, bailing line, pumps and pump
tubing, filtering equipment, trowels, bowls (for compositing or homogenizing soil samples) and
beakers. Care should be taken to properly decontaminate this equipment or cross-contamination
could occur.
The decontamination of sampling equipment should be designed based on the suspected
contaminants of concern. Typically decontamination will include scrubbing with soapy water,
and rinsing with tap water and distilled water. In some cases, dilute acid (e.g., dilute nitric acid)
and/or solvents (methanol or hexane) may be used. However, in general, use of solvents should
be avoided.
2.4.11.3 Field Analytical Equipment Decontamination
Field analytical equipment that may contact the sample media includes water level
meters, pH or specific ion probes, thermometers, and borehole geophysical equipment. This
equipment should be decontaminated prior to use, between sampling locations, and after the
conclusion of the field program. Decontamination of this equipment should follow
manufacturers recommended procedures and should prevent cross contamination.
2.4.12 Investigation Derived Waste
Site characterization field investigations may result in the generation and handling of soil,
groundwater, drilling muds, decontamination products, personal protective equipment/garments,
and other materials that may pose a risk to humans or the environment if not properly managed.
Prior to initiating any type of field sampling activity, it is important to plan the handling of waste
2 - 46
products that will be generated. Not only is this important from an exposure or human/
environmental protection basis, but improper or inefficient handling of such wastes could result
in excessive costs or noncompliance with certain environmental regulations (e.g., RCRA, Toxic
Substances Control Act [TSCA]). For these reasons, it is recommended that a IDW Management
Plan (IDWMP) be incorporated into the SAP. The format of the IDWMP should reflect the
complexity of the field investigation, the amount of information known about the site (i.e., what
degree, if any, of contamination exists at the site based on historical use or previous sampling
investigations), and the experience of the field team with respect to IDW management.
This section presents an overview of possible IDW management options, discusses the
regulatory requirements of these options, and outlines general objectives for the management of
IDW during site characterizations. This section is based on the document entitled “Management
of Investigation-Derived Wastes During Site Inspections” (USEPA 540 G-91-009 - May 1991)
and various other regulatory memorandums or federal guidance, including Department of
Defense and other state guidelines.
2.4.12.1 IDW Management Considerations
IDW management considerations include identification of disposal and management
options that are protective of human health and the environment, and comply with either state or
federal laws. In general, best professional judgment should be exercised to determine whether an
option is protective.
The LRS should consider the following when developing a plan to manage IDW:
The potential degree of contamination that may be exhibited by the IDW;
The potential exposure to human health or the environment to concentrations
of contaminants in excess of the De Minimis or other appropriate standards;
Safety and aesthetic factors associated with the disposition of the wastes (if
the management option is to leave the IDW on site); and
State or federal regulatory requirements for proper handling and treatment
/disposal.
More information on RCRA wastes, including Land Disposal Restrictions (LDRs) and
TSCA wastes can be found in the following references:
USEPA. 1989 OSWER Directive 9347.3-05FS
40 CFR Part 260 (Hazardous Waste Management System: General)
40 CFR Part 261 (Identification and Listing of Hazardous Wastes)
USEPA. 1990. PCB Guidance Manual, EPA/540/G-90/007, August.
40 CFR Part 761 (PCBs)
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2.4.12.2 General Objectives for IDW Management
In addition to ensuring that the IDW management is protective of public health and the
environment and conducted in accordance with applicable regulations, site managers need to
consider two general objectives: (1) minimize the amount of IDW when possible; and (2)
manage the IDW as part of the final remedial action for the site.
Minimizing the volume of IDW should be considered during the scoping of the field
investigation and the development of the IDWMP. Potential ways to reduce the amount of IDW
include the following:
Select field techniques which do not result in excessive IDW (e.g., soil gas surveys,
GeoprobeR sampling, direct push sampling techniques);
Segregate wastes from “hot areas” from other areas which may not be
contaminated; and
Do not containerize IDW from background locations, which are known or
suspected to be non-contaminated.
Managing the IDW as part of the final remedial action should consider the following:
Backfill test pits and soil borings in areas where remediation is likely to occur
(based on background information, field observations, or previous
investigative data);
If the IDW is containerized, manage the treatment/disposal as part of the
remedial actions for the various site media.
2.4.12.3 IDW Characterization
Management of IDW should be consistent with guidance provided in Management of
Investigation-Derived Wastes During Site Inspections, (USEPA, 1991).
In order to determine the appropriate disposal option, it may be necessary to characterize
the IDW via analytical testing. The most accurate way to characterize the waste is to obtain
samples from the IDW. Using the analytical results from the site characterization program
(without sampling the IDW) can also be employed in some cases.
Characterizing the IDW is more accurate and representative if the IDW is segregated
during the field program (i.e., known contaminated IDW is contained separately from potentially
contaminated IDW), and sampled accordingly. The objective is to obtain a sample that is
representative of each waste source so the IDW is disposed properly and cost-effectively.
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FIGURE 2-4: IDW MANAGEMENT DECISION TREE
Plan for IDW Handling in
Work Plan Including Techniques
Minimizing Waste Generation
Characterize Waste (Use
Available Information and
Best Professional Judgment)
Determine Whether On-Site
Handling of IDW Would Create
Increased Risks at the Site
Plan for Waste Management
According to IDW
Characteristic
RCRA Hazardous and
High Concentration PCBs
RCRA Non-Hazardous
Dispose
Off Site (1)
Leave
On-Site (2)
(Soil Only)
Dispose
Off Site (3)
Leave
On Site
b a b a
To Figure 3 To Figure 2 To Figure 3 To Figure 2
(1) Soil cuttings, ground water, and decontamination fluids creating increased hazards at the site should be disposed off-site. Before and after the site investigation, determine anticipated waste quantity and
applicable regulations for waste generators.
(2) If not prohibited by other legally enforceable requirements such as state ARARs. (3) Justified only in rare circumstances when a RCRA nonhazardous waste is a state hazardous waste and state legally enforceable requirements call for waste removal, or if leaving the waste on-site would
significantly affect human health and the environment.
Source: USEPA 540G-91-009 – Management of Investigation Derived Wastes During Site Inspections – May 1991
2 - 49
FIGURE 2-5: IDW MANAGEMENT DECISION TREE
On-Site Handling
(Approach Cannot Violate Federal
and State Regulations) a
Inform Owner that IDW
Will be Left On-Site
Soil
Clean PPE & DE
Decon Fluids
Ground Water
To Existing
Disposal/treatment Unit
(if Suitable) (2)
On-Site Industrial
Dumpster (1) Put Back
to Boring
Onto Ground
To Existing
Disposal/Treatment
Unit (2)
Discharge Next
to Well
Spread Around
Boring and
Cover With
Surface Soil
(Only RCRA
Nonhazardous
and PCB-Free)
Put in Pit
(RCRA
Waste within
an AOC Unit
Covered
With Surface
Soil)
(1) Clean PPE and DE may also go to the nearest landfill or to a dumpster.
(2) If the receiving unit meets the off-site policy acceptability criteria.
Source: USEPA 540G-91-009 – Management of Investigation Derived Wastes During Site Inspections – May 1991
(RCRA Hazardous and Nonhazardous) (Only RCRA Nonhazardous)
From Figure 1
2 - 50
FIGURE 2-6: IDW MANAGEMENT DECISION TREE
Off-Site
Disposal
Initiate Subcontracting Process
Inform Owner That IDW Will be Stored
b
From Figure 1
PPE and DE
Decontaminate
PPE and DE
Double Bag (1)
Or Drum(2)
Store (3)
Soil Decontamination
Fluids (5)
Groundwater
Containerize
Store(3)
Finalize Subcontractor for
Testing, Pickup and Disposal
Test
Pickup and
Dispose
TSCA Facility Municipal
Landfill (4) On-Site
Dumpster (1) RCRA Hazardous
Waste Facility(2) POTW Other Facilities
(1) Only RCRA nonhazardous waste.
(2) Only RCRA hazardous waste generated in quantities greater than 100 kg/month when sent off-site. (3) In accordance with accumulation requirements for RCRA hazardous wastes.
(4) Only if the conditionally exempt small quantity generator exception applies.
(5) If the conditionally exempt small quantity generator exception applies, off-site disposal of decon fluids may not require subcontracting.
Source: USEPA 540G-91-009 – Management of Investigation Derived Wastes During Site Inspections – May 1991
2 - 51
Soil IDW that is containerized in drums can be efficiently characterized by compositing
representative samples from each drum as long as the drums are segregated by area of concern.
It makes no sense to obtain a composite sample from six “clean” drums and one “hot” drum
since you may have a result that indicates that all of the IDW is contaminated when in reality,
only one of the six drums is contaminated. Conversely, you may also falsely assume that all of
the drums are non-hazardous when in fact one of the drums may be hazardous. This is why it is
important to segregate “hot” wastes from other wastes.
Liquid IDW is usually containerized in either storage containers (1,000- and 2,500-gallon
capacity containers are the norm) or 55-gallon drums. If drums are used to containerize the
liquid IDW, either a composite sample should be collected; a sample of the suspected worst case
drum, or the analytical results from the sampling program should be used to characterize the
wastes. In the latter case, it is important to identify the monitoring well location on the drums so
that the analytical results can be properly correlated.
Using the field program analytical results can also be used for soils, if the soils are
segregated by area of concern or the soils are containerized in drums and properly identified by
location.
The analytical suite for characterizing IDW should match the analytical suite for which
you are testing. In cases where the LRS is unable to use generator knowledge or previous sample
analyses to demonstrate the nature of any generated wastes, it will be necessary to analyze for
RCRA hazardous waste constituents (ignitability, reactivity, corrosivity, and/or leachability/toxic
compound leaching procedure [TCLP]) prior to shipment to an off site treatment/disposal
facility.
2.4.12.4 IDW Disposal Options
The disposal option selected should be based on best professional judgment and consider
the following:
Volumes and types of wastes requiring disposal;
Risks posed by disposing the IDW at the site without any containerization or
characterization;
Compliance with state and federal regulations;
Whether the IDW can be managed as part of a future remedial action at the
site;
Public perception and safety;
Compliance with transporter and disposal facility requirements.
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To assess whether the IDW possesses a health or environmental risk, West Virginia De
Minimis Standards can be used as a guide for this determination. The De Minimis Standards
represent contaminant specific acceptable concentrations for soil and groundwater.
Figures 2-4 to 2-6 provide an IDW Management Decision Tree that can be used by the
LRS to evaluate IDW disposal options (USEPA, 1991).
2.4.13 Modeling
The LRS may use modeling, to determine whether a source of contamination on the site
will cause the applicable risk-based standards to be exceeded either at the property boundary, or
at an off-site well. The purpose of this section is (1) to provide guidelines and references that
will assist the LRS in selecting an appropriate groundwater model, (2) to discuss the type of
information that must be submitted for review when requesting approval to use the proposed
model, and (3) discuss how the results of the modeling should be reported.
2.4.13.1 Model Selection
The first thing that should be considered is whether it is even practical to attempt to
model groundwater flow and/or contaminant transport at the site. Perhaps the most important
part of the modeling process is choosing the correct model to use with the available data and site
conditions.
In general, most computer models have been designed to simulate transport in porous
media like silts, sands and gravel. These models cannot be effectively used to study a site where
contaminants may have moved into fractured basalt or shale, or other formations that cannot be
considered typical porous media. Sufficient data must be available to run the selected model.
If adequate site-specific data are not available, justifications will need to be made
regarding the use of generic values or another approach must be considered. It may be more
cost-effective at some sites to perform leaching tests or install monitoring wells than to do a
modeling study.
There are many sources of published guidance to help model users with most aspects of
modeling, such as: model selection, correct application, calibration, and verification. ASTM has
published several documents dealing with several of these issues and provides acceptable
guidance. See also references such as Selection Criteria for Mathematical Models Used in
Exposure Assessments: Ground-Water Models (USEPA, 1988) and/or Modeling of Soil
Remediation Goals Based on Migration to Groundwater (USEPA, 1991) for descriptions of
available models. The National Research Council (1990) also provides an excellent discussion
of the inherent limitations and uncertainties in using models to assist in the decision-making
process.
The proposed models must be:
Peer-reviewed
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Model-verified (shown to produce reliable and mathematically accurate
results for all functions of the model)
Consistent with actual physical conditions throughout the modeled area. The
assumptions and limitations of the computer code, mathematical solution,
technology used and computer code structure must be consistent with the
actual physical conditions throughout the modeled area and the application of
the model
Used consistent with the model’s documentation and all stated assumptions
Calibrated to geologic, hydrogeologic, and physical conditions throughout the
modeled area
Field-validated (if possible) to determine if there exists a consistent
comparisons between the modeled, or predicted, conditions and observed field
conditions for the area being modeled.
The following analytical one-dimensional models are considered to be acceptable for
modeling groundwater in the saturated zone, as long as they are used according to their
limitations and intended uses:
MULTIMED
AT123D
The following numerical models are considered to be acceptable for modeling
groundwater in the saturated zone, as long as they are calibrated to property conditions and are
used according to their limitations and intended uses:
FLOWPATH (2D)
MODFLOW (3D)
MT3D (in conjunction with MODFLOW)
The following models are considered to be acceptable for modeling in the vadose zone,
as long as they are calibrated to site-specific conditions and are used according to their
limitations and intended uses:
VLEACH
SESOIL
MULTIMED
Selection of other models may be proposed by the LRS in the site characterization work
plan.
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2.4.13.2 Surface Water Modeling Selection
Computer modeling can be used to predict the instream concentrations of contaminants
which are introduced into surface waters via storm water runoff (storm water models) or
groundwater infiltration (surface water models). However, in many cases it is better to simply
sample the surface water body directly. Like the previously described groundwater models,
appropriate model selection is critical to the prediction of contaminant concentrations. Although
detailed hydrologic and hydraulic analysis will not be necessary for all remediation sites, it may
be required under certain circumstances. Hydrologic and hydraulic analysis may be utilized in
conjunction with the activities described in Sections 2.4.5 and 2.4.8. Three types of analysis that
may be needed are:
Estimating peak discharges
Hydraulic analysis
Low Flow analysis
Fate and transport analysis
Acceptable methodologies for these analyses are described in the following sections.
Estimating Peak Discharges
Estimating peak discharge for various storm events may be necessary on some
remediation sites. Flood Insurance Studies (FISs) have been established for many communities
by the Federal Emergency Management Agency (FEMA) as part of the National Flood Insurance
Program. If a FIS exists for the local community, hydrologic data included in the study should
be utilized as deemed appropriate. If FEMA data is not available for a particular watercourse,
peak discharges may be estimated using SCS methodology.
One of the following hydrologic models may be used to estimate peak discharges:
USDA, SCS. June 1986. Urban Hydrology for Small Watersheds, Technical
Release 55 (TR-55).
USDA, SCS. May 1982. Technical Release 20 (TR-20), Project Formulation
- Hydrology.
US Army Corps of Engineers. September 1990. Hydrologic Engineering
Center, HEC-1, Flood Hydrograph Package.
Hydraulic Analysis
Hydraulic analysis may be used to:
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Estimate floodplain limits
Determine the capacity of existing or proposed drainage systems
Estimate the distance downstream that an accidental discharge may impact
Estimate the time to impact at various locations downstream due to an
accidental discharge
Hydraulic information contained in the FIS may be utilized as deemed appropriate. If
FEMA data is not available, one of the following programs should be utilized:
Federal Highway Administration. January 1994. Culvert Analysis, HY-8.
U.S. Army Corps of Engineers. September 1990. Hydrologic Engineering
Center. HEC-2, Water Surface Profiles.
U.S. Army Corps of Engineers. April 1997. Hydrologic Engineering Center,
HEC-RAS, River Analysis System.
The HY-8 Computer Program may be used to analyze culvert systems. This program
determines capacities, headwater elevations, velocities, and other hydraulic characteristics of
culvert systems. It should be noted that Manning’s equation can be used to analyze channels or
culverts under steady uniform flow conditions.
Either the HEC-2 or the HEC-RAS program may be used for a detailed backwater
analysis of a stream. These programs are used for calculating water surface profiles as well as
numerous other hydraulic parameters for steady gradually varied flow in natural or man-made
channels.
Low Flow Analyses
Estimates of low flow values may be necessary to establish effluent limitations or to
estimate the impact of discharges into a stream. Low flow values should be based on gage
records of the stream under investigation or gage records on nearby streams with similar
hydrologic characteristics. A Log-Pearson Type III analysis should be performed on the gage
records to estimate the low flow value. Gages on nearby streams should be correlated with data
from the stream under investigation if possible. Information on gages in the project area can be
obtained from the USGS, Water Resource Division. Most USGS offices will perform the
analysis for a small fee.
Toxicant Fate and Transport Models
There are numerous sources of information for guidance on selection, application and
interpretation of surface water models such as the U.S. EPA's internet site and the Technical
Support Document for Water Quality Based Toxics Control. Specific information on modeling
2 - 56
alternatives and many models are available from the US EPA Center for Exposure Assessment
Modeling in Athens, Georgia. Most models are supported by guidance documents or technical
manuals, which include detailed descriptions of the models assumptions and limitations, and the
data and quality assurance necessary to operate the models.
Like the groundwater models, the surface water fate and transport models must also be:
Peer-reviewed
Model-verified
Consistent with actual physical conditions throughout the modeled area
Used in a manner consistent with the model's documentation and all stated
assumptions
Calibrated to hydrologic, geologic and physical conditions in the area
Field-validated (if possible) to determine if there are consistent comparisons
between predicted and observed parameters.
The following toxicant fate and transport models would be considered acceptable for use
providing assumptions inherent in the models are accurate and they are used according to their
limitations and intended uses.
DYNTOX
ESAMS-II
WASP4
HSPF
SARAH2
MINTEQA2
Selection of other models may be proposed by the LRS in the site characterization work
plan.
2.4.13.3 Model Approval
After a model has been selected and it has been determined what values will be used for
most of the input parameters, the LRS should request WVDEP approval for use of this model at
the site. The request should include a description of why this model is appropriate for the site
including supporting documentation. The documentation must be sufficiently detailed and
include relevant technical information about the model, such as:
2 - 57
the model name, version number and date
the names of the author(s) and company
the intended use of the model as described by the author/company
the governing mathematical equations and boundary conditions
the assumptions used in the development of the model
comparisons of the proposed model to other established models if available
an example of a field application of the model should also be included.
2.4.13.4 Model Application
The purposes of a model could include:
Predict if soil contamination will leach into the groundwater
Predict if contaminants will migrate to the receptors of concern at
concentration above acceptable levels
Predict the most effective remedial alternative or design
After obtaining WVDEP approval, the application of the model can proceed. Since
concentrations in a contaminant plume vary spatially and temporally, it is important to define a
specific location and time for which the contaminant levels must be modeled. For example, the
point of compliance may be 10 meters from the downgradient edge of the contaminated zone. A
sufficient time period must be modeled to predict the maximum concentration of each
contaminant at the point of exposure.
The LRS (or designated modeler) should use input data collected from the modeled area
to calibrate the model to conditions throughout the modeled area. Whenever the modeler cannot
rely upon input parameters collected from within the modeled area, the modeler must provide
justification for why input parameters were not collected from within the modeled area, and
demonstrate that the model is being calibrated and used properly. The modeler should validate
the model predictions (if possible) with empirical data collected from the locations of the model
output.
Modeling results should be presented in a summary report. This report should fully
document the model and include model input parameters. In addition, site-specific sensitivity
test results should be included for each parameter determined to be sensitive, using a range of
input values considered to be reasonable for the site. The WVDEP may also ask for complete
copies, either hard copies or electronic copies, of all input and output files used in your site-
specific study.
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2.5 Background Concentrations
The Rule specifies that where the De Minimis Standard is below natural background and
where the Uniform and Site-Specific Risk-Based Standards are below anthropogenic
background, that natural background may be used in place of the De Minimis Standard, and
natural or anthropogenic background may be used in place of the Uniform and Site-Specific
Risk-Based Standards.
2.5.1 Definition of Background
Natural background refers to the concentrations of elements that occur naturally in the
earth, without any human interference. Background concentrations of naturally-occurring
elements in both soils and groundwater vary greatly depending on soil types, geologic strata, and
depositional environment. Anthropogenic background refers to concentrations of elements that
occur over a widespread area as a result of human activities.
Methods to ascertain background levels are described in Appendix B. Alternatives to the
methods for determining background levels described in this guidance should be approved by the
director. No single method is appropriate for all contaminants, media, or sites, so a case-by-case
evaluation is required and expert judgment is needed to design an appropriate strategy to
determine background levels, particularly where anthropogenic sources are involved. A weight-
of-evidence approach, where several independent lines of evidence are used to determine
anthropogenic background, is preferred. For some sites, this may involve demonstrating that a
release is confined to a “hot spot” or other aggregated area of contamination and has not become
widely dispersed beyond a site, but that other human-activities unrelated to site activities have
resulted in low levels of the contaminant being widely dispersed across as well as beyond the
site. Unfortunately, it is extremely difficult to prove that a contaminant released at a site did not
move to those other locations and is present due solely to activities unrelated to operations at the
site.
Examples of methods to support a determination of anthropogenic background include
the following:
1. Documentation of another area-wide source (outside the site) for the
contaminant in soils, groundwater, or surface water. This approach is
particularly useful for groundwater contamination where the flow rate and
direction of the aquifer is well defined. Where ground water monitoring
wells upgradient of the site indicate the presence of anthropogenic
contaminants, these levels provide an indication of anthropogenic
background. Caution should be used for aquifers that are not well defined, or
contaminants that may move in an unexpected fashion (e.g., DNAPLs).
2. Statistical methods to compare upgradient and downgradient samples should
account for spatial and temporal correlations among samples (See Gilbert,
1987).
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3. Use of geostatistics or other spatial statistical approaches to demonstrate the
extent of spread of a contaminant from the on-site source, relative to
anthropogenic background.
4. Vertical and/or horizontal stratification of contaminant concentrations
throughout a region, showing that anthropogenic sources contribute to
elevated levels of the contaminant.
5. Chemical fingerprinting of releases, particularly where multiple contaminants
or suitable tracer contaminants are involved, to demonstrate which
contaminants are associated with a release versus off-site sources. Levels of
contaminants in samples may provide evidence of an anthropogenic
background level when patterns of chemical constituents associated with site-
related releases are distinct from those found with releases associated with
anthropogenic background. The presence of release-specific ratios of
constituents, or specific tracer compounds in samples are examples of this
approach. To be useful, the tracer compound(s) should have similar transport
and fate characteristics as the contaminant of concern so that its distribution
provides a reliable estimate of the distribution and concentration of the
contaminant of concern.
6. Historical records of past releases documenting the source(s) of
anthropogenic contaminants. Baseline data pre-dating on-site releases are
particularly useful in this regard. Records of past releases provide supporting
information.
7. Sampling of carefully selected areas outside the site to demonstrate that
contaminants are widespread. Sample area selection criteria should be
approved with the work plan in advance and should assure that site-related
activities did not contribute to sample area contaminant levels.
2.5.1.1 Establishing Background for the De Minimis Standard
Published values of background concentrations for soil, sediment, groundwater, and
surface water are to be used for the De Minimis Standard.
Soils
Natural background levels of many elements in soil are described in published literature.
This information can be used for comparing natural background levels with the De Minimis
Standard. Mean values from West Virginia soils are provided by Shacklette and Boerngen
(1984), while Dragun and Chiasson (1991) give background levels for the Eastern United States.
Table 2-3 provides background mean concentrations, standard deviations, and minimum and
maximum values for a range of elements. West Virginia-specific information is primarily relied
upon, and supplemented by Eastern United States (U.S.) data where the sample sizes in West
Virginia are too small.
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Sediments and Surface Water
Sediments and surface water are not a media considered in the De Minimis Standard,
unless surface water is a drinking water source.
Groundwater
Until a compilation of information for background levels in groundwater for West
Virginia is put together for use with the De Minimis Standard, refer to Subsection 2.5.1.2 of this
guidance on establishing background for the Uniform and Site-Specific Risk-Based Standards.
2.5.1.2 Establishing Background for the uniform and Site-Specific Risk-Based Standards
Because background levels are greatly influenced by soil type and geologic strata, site-
specific sampling is a more accurate method of determining an appropriate background value.
The Uniform and Site-Specific Risk-Based Standards permit the use of anthropogenic
background levels as the standard where anthropogenic background levels exceed the risk-based
level. Methods to identify sample location and numbers of samples to collect for determining
background in soils, groundwater, and surface water are discussed in Appendix B. Sediments
may not be evaluated under the Uniform Standard.
2.5.1.2.1 Natural vs. Anthropogenic Background
Natural vs. anthropogenic background levels cannot always be easily established. This
occurs because some contributors to anthropogenic background are decades, or centuries old.
Examples include the use of arsenical pesticides in the early 1900s, the effects of mining from
the 1800s onward, etc. As a result, it may not always be useful to try to determine whether
background levels are natural or include some component of anthropogenic activity. However, it
is appropriate to use any site-specific determination of background, whether it includes an
anthropogenic component or not, for comparison to the Uniform and Site-Specific Risk-Based
Standards.
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Table 2-3: Natural Background Levels of Inorganics in Soil in West Virginia and
Surrounding Areas
Element
Sample
Size
Mean
(ppm)
Std. Dev.
Min
Max
Source
Al 10 63,300 10,000 50,000 > 100,000 Shacklette & Boerngen
As 10 8.64 2.63 5.90 13.00 Shacklette & Boerngen
B 7 34 11.34 20 50 Shacklette & Boerngen
Ba 10 360 96.61 300 500 Shacklette & Boerngen
Be1
10 0.75 0.82 nd 2
2.0 Dragun & Chiasson
Ca 10 1,500 800 400 2,500 Shacklette & Boerngen
Co 10 13.7 4.37 7.0 20.0 Shacklette & Boerngen
Cr 10 46 15.78 30 70 Shacklette & Boerngen
Cu 10 22.0 5.87 15.0 30.0 Shacklette & Boerngen
F 9 223 80.47 100 400 Shacklette & Boerngen
Fe 10 28,500 15,644 15,000 70,000 Shacklette & Boerngen
Ga 10 17.50 5.40 10.00 30.00 Shacklette & Boerngen
Hg 10 0.14 0.13 0.02 0.44 Shacklette & Boerngen
K 10 13,100 3,200 8,100 18,700 Shacklette & Boerngen
La 10 44.0 13.50 30.0 70.0 Shacklette & Boerngen
Li 10 34.3 8.98 21.0 49.0 Shacklette & Boerngen
Mg 10 3,200 1,300 2,000 5,000 Shacklette & Boerngen
Mn 10 770 368.3 300 1,500 Shacklette & Boerngen
Na 10 3,800 2,200 1,500 7,000 Shacklette & Boerngen
Nb 8 13 3.72 10 20 Shacklette & Boerngen
Ni 10 23.00 7.53 15.00 30.00 Shacklette & Boerngen
Pb 10 16.50 4.12 10.00 20.00 Shacklette & Boerngen
Sb1.4
131 0.76 -- 3
< 1.0 8.80 Dragun & Chiasson
Sc 10 9.10 2.77 5.00 15.00 Shacklette & Boerngen
Se 10 0.465 0.226 < 0.1 0.80 Shacklette & Boerngen
Sn1,4
131 1.50 -- 3
< 0.1 10.0 Dragun & Chiasson
Sr 10 72.00 16.87 50.00 100.00 Shacklette & Boerngen
Ti 10 4,500 1,700 2,000 7,000 Shacklette & Boerngen
U1,4
130 2.70 -- 3
0.29 11.0 Dragun & Chiasson
V 10 65 18.41 30 100 Shacklette & Boerngen
Y 10 28 9.19 20 50 Shacklette & Boerngen
Yb 10 3.1 0.74 2.0 5.0 Shacklette & Boerngen
Zn 10 60 18 40 98 Shacklette & Boerngen
Zr 10 220 58.69 150 300 Shacklette & Boerngen
Notes: 1. Values from Dragun & Chiasson were used due to small sample size In Shacklette & Boerngen paper. Dragun & Chiasson
calculated the mean and standard deviation using the detection limit for values reported as “<[detection limit]”, and using
zero for values reported as “not detected”.
2. nd indicates non-detect
3. -- indicates value not available
4. - Data for West VA were not available, therefore, values for Eastern U.S. soils were used.
5. Mean and standard deviation were calculated using one-half the detection limit for values reported as “<[detection limit]”.
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2.5.2 Comparison of Site Contaminant Concentrations to Background
The medium sampled influences the kind of statistical comparisons that can be made with
background data. If samples are not taken randomly because they are purposely placed (such as
with ground water well monitoring or air monitoring stations) the average station value is not an
appropriate measure to test the statistical hypothesis for the one-tailed test. For this reason,
determinations of background in groundwater are usually based on comparisons with upgradient
wells. Statistical comparisons of downgradient versus upgradient well samples may include
multiple comparison procedures, upper tolerance limits, or other methods approved by the
director as described in 33CSR1.4.11. Consult Subsection 2.4.7 of this guidance for details on
groundwater monitoring. Additional guidance for statistical comparison of groundwater data
may be found in USEPA (1989, 1996a). Supplementary guidance for statistical comparisons of
soil data may be found in USEPA (1996b,c).
Methods for comparison of site concentrations with background are given in Appendix B.
2.5.2.1 When Site Contaminant Concentrations are Less than Background
It is generally impractical and economically unjustified to remediate a site to levels below
those which occur naturally. When site contaminant concentrations are determined to be less
than background by appropriate statistical tests as described in Appendix B; no site remediation
will be required.
2.6 Contaminants of Concern
The data collected at the site should be reviewed and determined to be sufficient for risk
assessment purposes prior to deciding on the list of COPCs. As a general rule, the sampling data
is likely to be sufficient if the samples are representative of the exposure area; the data quality
conforms with the guidance in Subsection 2.4.1 and 2.4.2; the samples have been collected and
handled in accordance with standard procedures for the collection methodology; and the samples
were analyzed in accordance with appropriate laboratory methodologies and established
protocols (See Subsection on 2.4).
Chemicals detected in at least one sample (even at levels below Practical Quantitation
Limits (PQL) in a given medium at the site should be considered COPCs and should be carried
through the screening assessment or risk assessment unless there is specific, justifiable rationale
for dropping the contaminant from the risk characterization. The final list of contaminants which
will be carried through the risk assessment after the selection process described below is
conducted is termed the contaminants of concern (COCs). The selection of COCs should be
evaluated considering conditions present at each individual site. The risk assessment portion of
the report should document the process of identifying the COCs and list the chemicals that are
identified for both the human health and ecological risk assessment. The specific basis for
eliminating a chemical detected at the site from the list of contaminants of potential concern
should be clearly documented. The following subsections (2.6.1 through 2.6.5) outline
acceptable reasons for eliminating contaminants. Contaminants may be eliminated for other
reasons upon approval by the Director.
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2.6.1 Field or Laboratory Contaminants
Contamination may be introduced into a sample during sample collection, transport, or
laboratory handling and analysis. A variety of quality control samples such as trip, equipment,
laboratory calibration, and method blanks should be collected and analyzed to determine whether
contaminants are being introduced by field or laboratory practices (See Subsection 2.4.1). A trip
blank, which is made up in the laboratory and travels with the field team to the site and back
before analysis, is subject to potential contamination from the air to which the containers are
exposed. An equipment blank also travels to the field, but is opened at the site and used in the
same manner as a sample (e.g., poured through sampling equipment), thus discriminating
contamination due to field procedures. A laboratory calibration blank is placed in a laboratory
instrument without the reagents with which site samples are treated, thus discriminating
contamination due to the laboratory equipment or the water used in the laboratory. A method
blank is manipulated and treated with the same reagents as the site samples, thus discriminating
contamination due to the reagents or laboratory glassware.
A careful review of quality assurance and quality control data should be conducted as
part of an investigation to avoid including chemicals attributable to sampling or laboratory
activities in the risk assessment, while ensuring that chemicals which are site-related are not
eliminated from further evaluation. When assessing the potential for sample contamination,
USEPA (1989, 1992) recommends the following rule of thumb for common laboratory
contaminants (e.g., acetone, 2-butanone, methylene chloride, toluene, and the common phthalate
esters): consider sample results positive only if the concentration in the sample is more than ten
(10) times the maximum detected in any blank; otherwise treat the sample as nondetect. If the
contaminant in the blank is not one of these common laboratory contaminants, consider sample
results positive only if the concentration in the sample is more than five (5) times the maximum
detected in any blank; otherwise, treat the sample as nondetect. An exception to this rule may be
if these contaminants are otherwise associated with the site based on their history of prior use at
the site.
2.6.2 Low Concentrations and Low Frequency of Detection
Substances detected at low concentrations and low frequency may be omitted from the
risk assessment process. The purpose of this criterion is to eliminate from the risk assessment
any substance that is not present consistently enough or at high enough concentrations to
contribute significantly to exposure.
2.6.2.1 Low Concentrations
For a chemical to be identified as a contaminant of concern, it must be present in a
concentration above the detection limit of an appropriate method. Some compounds, e.g., those
which biomagnify in the food chain or for which synergistic interactions have been reported,
may cause health risks at levels below the detection limit of some standard methods, so care
must be taken not to rule out COCs prematurely. The method detection limit (MDL) is the
smallest concentration of a chemical, which can be accurately measured considering the
instrumentation and background noise. As the chemical concentration approaches the MDL, the
level of confidence in accurate quantitation decreases. For use in risk characterization, the
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Guidance for Data Usability in Risk Assessment (Part A) Final (USEPA, 1992) recommends the
use of the sample quantitation limit (SQL), which is the MDL adjusted to reflect sample specific
action, or the MDL itself. Instrument detection limits should never be considered appropriate for
use in the risk assessment. The practical quantitation limit (PQL), or the MDL multiplied by a
factor of 2 to 5, may be appropriate unless the PQL is unusually high. Site specific conditions
should be considered in determining which quantitation limit is used.
Data may be qualified due to concerns regarding chemical identification, chemical
concentration, or both. One of the most commonly encountered types of data qualifiers are “J”
values, used in the USEPA Contract Laboratory Program (CLP). The use of the “J” qualifier
may indicate that the identification of the contaminant is uncertain or approximate or that the
concentration of the contaminant in the sample is estimated. USEPA (1989) recommends the
use of J-qualified data, but cautions that care should be exercised if the risk is being driven by
the qualified data results.
2.6.2.2 Low Frequency of Detection
The frequency of detection will be evaluated at each site based upon the total number of
samples collected, the sampling design, and the total area sampled. In order to establish that the
frequency of detection is low, the total number of samples collected must be adequate to
characterize the extent of contamination at the site. The number for what constitutes low
frequency of detection will be a function of total sample size and, as such, it would not be
appropriate to consider contaminants detected in one to two samples as low frequency when the
total sample size was less than ten samples.
The samples included in the total sample size should be collected in the same medium
with similar characteristics. For example, in soil samples, the samples used to develop frequency
of detects should be collected at similar depths in areas where the soil has similar characteristics
(e.g., soil collected in a flood plain would differ from that collected out of the flood plain).
When determining whether the frequency of detection of a particular contaminant is low,
it is also important to consider the spatial relationship of that sample relative to other samples at
the site. For example, a contaminant may only be detected in 2 out of 20 samples, but those two
samples may represent a source area or “hot spot” which may need to be remediated to prevent
degradation of other media (e.g., groundwater).
2.6.3 Unusually High Sample Quantitation Limits
Sample quantitation limits for a particular chemical in some samples may be unusually
high due to one or more sample-specific problems (e.g., matrix interferences). Sometimes these
values greatly exceed the positive results reported for the same chemical in other samples from
the data set. The SQLs may be reduced by reanalyzing the sample or the samples may be
excluded from the risk assessment if they cause the calculated exposure concentration to exceed
the maximum detected concentration for a particular sample set (USEPA, 1989). If there are
numerous problems with a data set such that quantitation limit’s for the majority of the samples
are elevated, reanalysis and possibly resampling is indicated.
2 - 65
2.6.4 Comparison to Background
Contaminants of potential concern associated with a site should be evaluated in relation
to background conditions, either natural or anthropogenic, as appropriate. When chemicals are
present at levels which are consistent with background then those chemicals need not be carried
through the risk assessment process. This guidance addresses the determination of consistency
with background in much greater detail in Subsection 2.5.
2.6.5 Evaluate Essential Nutrients
Chemicals that are: essential nutrients present at low concentrations, and toxic only at
very high doses need not be considered further in the risk assessment. Examples of such
chemicals are iron, magnesium, calcium, potassium, and sodium (USEPA, 1989).
2.6.6 Screen Against De Minimis or Benchmark Levels to Identify COCs
In an effort to streamline the investigation and cleanup of properties, the WVDEP has
provided De Minimis human health screening levels for soil and groundwater media
contaminants. The screening levels are provided for residential land and water use and
industrial/commercial land use for soils. The screening levels are derived from the USEPA
Region III Risk-Based Concentration Tables, although the industrial risk based concentrations
have been modified to reflect a 1 x 10-5
carcinogenic risk and WV Groundwater Standards have
been inserted when available.
A contaminant of potential concern in soil may be screened against the human health De
Minimis standard to further refine the list of contaminants to be carried through the risk
assessment (either using the Uniform Risk-Based or Site-Specific standard), only if leaching to
groundwater, inhalation of volatiles, and ecological risk is not of concern (see Appendices D.4.5,
D.4.3.1, and C-2 respectively). If a site-specific ecological risk assessment is performed,
chemicals may be screened against available benchmarks to further refine the list of COCs. The
more conservative of the human health De Minimis or the ecological benchmark shall be used as
the screening value.
2.6.7 Additional Issues for Consideration
2.6.7.1 Chemical Species
It may be important to consider specific states of the chemicals when identifying COCs.
Depending on the specific state of the chemical that is present at the site, there may be different
health or environmental effects associated with the chemical. For example, differences in
oxidation states of metals can result in changes in absorption or toxicity (e.g., hexavalent
chromium is more toxic than trivalent chromium). In addition, some products may degrade over
time and products of degradation may have different toxicity parameters (e.g., vinyl chloride is
more toxic than trichloroethene). These factors should be considered when identifying
contaminants of concern.
2.6.7.2 Groups of Compounds
2 - 66
Some of the data collected for a site may be presented as groups of compounds (e.g.,
TPH). Data on groups of chemicals is not generally useful in the risk assessment process.
Toxicity information used to estimate risk is compound specific; therefore the estimation of risk
associated with exposure to compounds that are identified as a group can be highly inaccurate or
impossible, and as a result is not generally recommended. The individual contaminants are the
COCs, but, to simplify discussion within the risk assessment, may be described as groups of
compounds.
2.6.7.3 Tentatively Identified Compounds (TICs)
When gas chromatography-mass spectrometry (GC-MS) is used to analyze for the
presence of organic compounds, the instrument is calibrated for authentic chemical standards.
These standards represent the target compounds, which are being analyzed in the samples. A
target compound in an environmental sample is identified by matching its mass spectrum and
relative retention time to those obtained for the authentic standard during calibration.
Quantitation of a target compound is achieved by comparison of its chromatographic peak area
to that of an internal standard compound. When compounds are identified in the sample, but the
GC-MS instrument was not specifically calibrated for those compounds, they are designated as
TICs. The mass spectrum of the sample is compared to a computerized library of mass spectra,
but since no standard was calibrated for the TIC, the identification is less certain than for target
compounds. The Guidance for Data Usability in Risk Assessment (Part A) Final (USEPA, 1992)
identifies several techniques which can be used to increase the confidence in identification and
quantification of TICs.
The TIC data should be reviewed by an analytical chemist trained in the
interpretation of mass spectra and chromatograms;
The identification of the TICs should be checked against the chromatographic
retention indices or relative retention times. Use physical characteristics (e.g.,
boiling point or vapor pressure) to determine if identification is reasonable;
The TICs should be compared to available site information regarding past use
of the site and chemicals associated with prior uses of the site;
TICs can be compared to known analytical response characteristics for similar
compounds for better quantification.
The sample could be re-analyzed using an authentic standard.
It is also advisable to evaluate whether the TIC is likely to be associated with other
compounds detected at the site. The result may support the tentative identification or may aid in
making a decision regarding the need to re-sample.
The TIC may also be classified as belonging to a particular class of compounds, such as
polycyclic aromatic hydrocarbons, and may be discussed qualitatively in the risk assessment.
When dealing with TICs qualitatively, the impacts on cumulative site risk and overall uncertainty
2 - 67
should be discussed. The data should be reviewed by an experienced analyst to obtain an “order
of magnitude” estimate of the concentration, prior to any discussions of qualitative risk posed by
TICs. The concentrations of TICs v. concentrations of identified compounds should be
discussed in terms of the overall risk associated with the site.
2.7 Presentation of COCs in Tabular Format
Consider the creation of a separate table for each environmental medium (e.g., soil,
sediment, groundwater, surface water, fish tissue, indoor air, outdoor air, soil gas) for which
sampling data is available. Throughout the text and tables, present the data in a consistent
manner (e.g., ug/L for groundwater and mg/kg for soils). Arrange the data chronologically, if
appropriate (e.g., groundwater), and discuss in the text any apparent time trends in the data.
Present the number of times detected/number of times analyzed (frequency of detection), range
of sample quantitation limits, minimum and maximum concentrations, arithmetic mean and 95
percent upper confidence limit on the arithmetic mean (if applicable). If hot spots are identified,
they may be presented in separate tables.
2.8 References
2.8.1 Preliminary Characterization
American Society for Testing Materials (ASTM). 1997. E 1527-97 Standard Practice for
Environmental Site Assessment: Phase I Environmental Site Assessment Process.
2.8.2 Risk Assessment Data Requirements
United States Environmental Protection Agency (USEPA). 1989. Risk
Assessment Guidance for Superfund Volume I. Human Health Evaluation
Manual (Part A) Interim Final. Office of Solid Waste and Emergency Response.
Washington, D.C. EPA/540/1-89/002. March 1989.
United States Environmental Protection Agency (USEPA). 1989. Risk
Assessment Guidance for Superfund, Volume II: Environmental Evaluation.
Office of Solid Waste and Emergency Response. Washington, D.C. EPA/540/1-
89/001. March 1989.
United States Environmental Protection Agency (USEPA). 1992. Guidance for
Data Usability in Risk Assessment (Part A) Final. Office of Emergency and
Remedial Response. Washington, DC. Publication 9285.7-09A. April 1992.
United States Environmental Protection Agency (USEPA). 1995. Land Use in
The CERCLA Remedy Selection Process. Elliott P. Laws, Asst. Administrator.
OSWER Directive 9355.7-04. May 25, 1995.
2 - 68
United States Environmental Protection Agency (USEPA). 1997. Integrated Risk
Information System On-line Database. Environmental Criteria and Assessment
Office. Cincinnati, Ohio. www.epa.gov/docs/ordntrnt/ord/dbases/iris/index.html
2.8.3 Data Requirements for Remedial Action Design
United States Environmental Protection Agency (USEPA) Engineering Bulletin.
1992. Technology Pre-selection Data Requirements. EPA/540/S-92/009.
United States Environmental Protection Agency (USEPA). 1993. Guide for
Conducting Treatability Studies under CERCLA. Office of Research and
Development and Office of Emergency and Remedial Response. Cincinnati,
Ohio. EPA/540/R-93/519-A.
2.8.4 Data Requirements for Modeling
Luckner, L and W.M. Schestakow. 1991. Migration Processes in the Soil and
Groundwater Zone. Lewis Publishers, Inc. Chelsea, Michigan.
Tyler, L.D. and M.B. McBride. 1982. Mobility and Extractability of Cadmium,
Copper, Nickel and Zinc in Organic and Mineral Soil Columns. Soil Science,
134(3), pp 198-205.
Korte, N.E., J Skopp, W.H. Fuller, E.E. Niebla and B.A. Aleshi. 1976. Trace
Element Movement in Soils: Influence of Soil Physical and Chemical Properties.
Soil Science, 122(6), pp 350-359.
2.8.5 Investigation Techniques for Sampling and Analysis Plans
Aller, Linda, et al. 1989. Handbook of Suggested Practices for the Design and
Installation of Ground-Water Monitoring Wells. National Water Well
Association.
American Society for Testing Materials (ASTM). 1991. Test Method (Field
Procedure) for Instantaneous Change in Head (Slug Test) for Determining
Hydraulic Properties of Aquifers. D-4044-91 (Vol. 04.08).
American Society for Testing Materials (ASTM). 1991. Test Method (Field
Procedure) for Withdrawal and Injection on Well Tests for Determining
Hydraulic Properties of Aquifer Systems D-4050-91 (Vol. 04.08).
American Society for Testing Materials (ASTM). 1993. Practice for Diamond
Core Drilling for Site Investigation D-2113-83 - Reapproved 1993 (Vol. 04.08).
2 - 69
American Society for Testing Materials (ASTM). 1992. Test Method for
Penetration Test and Split-barrel Sampling of Soils D-1586-84 - Reapproved 1992
(Vol. 04.08).
American Society for Testing Materials (ASTM). 1990. Test Method for
Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a
Flexible Wall Permemeter. D-5084-90 (Vol. 04.09).
American Society for Testing Materials (ASTM). 1994. Test Method for
Infiltration Rate of Soils (in Field) Using Double Ring Infiltrometer. D-3385-94
(Vol. 04.08).
American Society for Testing Materials (ASTM). 1995. Guide to Site
Characterization for Environmental Purposes with Emphasis on Soil, Rock,
Vadose Zone, and Groundwater. D-5730-95a (Vol. 04.09).
American Society for Testing Materials (ASTM). 1994. Practice for Thin-
Walled Tube Sampling of Soils. D1587-94, (Vol. 4.08).
American Society for Testing Materials (ASTM). 1995. Practice for Soil
Investigation and Sampling by Auger Borings. D1452-80 - Reapproved 1995
(Vol. 4.08).
American Society for Testing and Materials (ASTM). 1986. Standard Test
Method for Deep, Quasi-Static, Cone and Friction-Cone Penetration Tests of Soil.
D3441-86 (Vol. 4.08).
American Society for Testing Materials (ASTM). 1993. Standard Guide for
Investigating and Sampling Soil and Rock. D420-93 (Vol. 4.08).
American Society for Testing and Materials (ASTM). 1990. Standard Practice
for Decontamination of Field Equipment Used at Nonradioactive Waste Sites.
D5088-90, (Vol. 4.08).
American Society for Testing Materials (ASTM). 1991. Guide for Soil Sampling
from the Vadose Zone. D4700-91 (Vol. 4.08).
American Society for Testing Materials (ASTM). 1993. Draft Standard Guide
for the Use of Hollow-Stem Augers for Geoenvironmental Exploration and
Installation of Subsurface Water-Quality Monitoring Devices. D18.21 Ballot 93-
03.
American Society for Testing Materials (ASTM). 1993. Draft Standard Guide
for the Use of Direct Rotary Drilling for Geoenvironmental Exploration and
Installation of Subsurface Water-Quality Monitoring Devices. D18.21 Ballot 93-
03.
American Society for Testing Materials (ASTM). 1993. Draft Standard Guide
for the Use of Air-Rotary Drilling for Geoenvironmental Exploration and
2 - 70
Installation of Subsurface Water-Quality Monitoring Devices. D18.21 Ballot 93-
03, April 28, 1993.
Bouwer, H and R.C. Rice. 1976. A Slug Test for Determining Hydraulic
Conductivity of Unconfined Aquifer with Completely or Partially Penetrating
Wells. Water Resources Research 12(3), pp.423-428.
Bouwer, H. 1989. The Bouwer and Rice Slug Test - An Update. Groundwater
27(3), pp. 304-309.
Christy, T.M. and S.C. Spradlin. 1992. The Use of Small Diameter Probing
Equipment for Contaminated Site Investigations. Groundwater Management
11:87-101 (6th NOAC).
Chiang, C.Y. et al., Characterization of Groundwater and Soil Conditions by Cone
Penetrometry. In: Proceedings (6th) NWWA/API Conference, Dublin, Ohio. pp.
175-189.
Driscoll, F.G. 1986. Groundwater and Wells: 2nd
Ed. Johnson Filtration Systems,
Inc. Minnesota.
Freeze, R.A. and J.A. Cherry. 1979. Groundwater. Prentice-Hall.
Hvorslev, M.J. 1951. Time Lag and Soil Permeability in Ground-Water
Observations, Bulletin 36. U.S. Army Corps of Engineers. Vicksburg,
Mississippi.
Kruseman, G.P. and N.A. deRiddler. 1991. Analysis and Evaluation of Pumping
Test Data. 2nd
Edition. ILRI Publication 47. Netherlands.
Lohman, W.W. 1972. Ground-Water Hydraulics. USGS-Professional Paper
708. USGPO.
New Jersey Department of Environmental Protection (NJDEP). 1992. Field
Sampling Procedures Manual. May, 1992.
United States Environmental Protection Agency (USEPA). 1983. Methods of
Chemical Analysis for Water and Waste, EPA/600/4-79/020, 1983 rev.
United States Environmental Protection Agency (USEPA). 1984. Geophysical
Techniques for Sensing Buried Wastes and Waste Migration. EPA/600/7-84/064.
United States Environmental Protection Agency (USEPA). 1985. Guide to
Decontaminating Buildings, Structures, and Equipment at Superfund Sites.
EPA/600/2-85/028.
United States Environmental Protection Agency (USEPA). 1992. RCRA
Groundwater Monitoring Technical Enforcement Guidance Document (TEGD).
Office of Waste Program Enforcement. OSWER Directive 9950.1.
2 - 71
United States Environmental Protection Agency (USEPA). 1986. Test Methods
for Evaluating Solid Waste, Office of Solid Waste and Emergency Response,
Washington, DC, November 1986 revised January 1995, SW-846 Third Edition.
United States Environmental Protection Agency (USEPA). 1987. A
Compendium of Superfund Field Operations Methods, Part 2. EPA/540/P-87/001
(OSWER Directive 9355.0-14).
United States Environmental Protection Agency (USEPA). 1987. Handbook -
Groundwater. EPA/625/6-87/016.
United States Environmental Protection Agency (USEPA). 1988. Field
Screening Methods Catalog: User’s Guide. EPA/540/2-88/005.
United States Environmental Protection Agency (USEPA). 1988. Guidance for
Performing Remedial Investigations and Feasibility Studies under CERCLA,
Interim Final. USEPA, Hazardous Site Evaluation Division, Office of Solid
Waste and Emergency Response, EPA/540/G-89/004. October.
United States Environmental Protection Agency (USEPA). 1988. Selection
Criteria for Mathematical Models Used in Exposure Assessments: Ground-Water
Models. EPA/600/8-91/038.
United States Environmental Protection Agency (USEPA). 1990. PCB Guidance
Manual. EPA/540/G-90/007. August.
United States Environmental Protection Agency (USEPA). 1991. Subsurface
Characterization for Subsurface Remediation. EPA/625/4-91/026.
United States Environmental Protection Agency (USEPA). 1991. Description and
Sampling of Contaminated Soils: A Field Pocket Guide. EPA/625/12-91/002.
United States Environmental Protection Agency (USEPA). 1991. Second
International Symposium, Field Screening Methods for Hazardous Waste and
Toxic Chemicals, EPA/600/9-91/028.
United States Environmental Protection Agency (USEPA). 1991. Handbook -
Ground - Water Volume II - Methodology. EPA/625/6-90/016.
United States Environmental Protection Agency (USEPA). 1991. Management
of Investigation-Derived Wastes During Site Inspections. EPA/540/G-91/009.
United States Environmental Protection Agency (USEPA). 1991. Modeling of
Soil Remediation Goals Based on Migration to Groundwater.
United States Environmental Protection Agency (USEPA). 1992. Guidance for
Performing Site Inspections under CERCLA, Interim Final. USEPA, Hazardous
Site Evaluation Division, Office of Solid Waste and Emergency Response,
EPA/540/R-92/021. September.
2 - 72
United States Environmental Protection Agency (USEPA). 1992. Preparation of
Soil Sampling Protocol: Techniques and Strategies NTIS PB-92220532.
United States Environmental Protection Agency (USEPA). 1992. Storm Water
Management for Industrial Activities (EPA/832/R-92/006).
United States Environmental Protection Agency (USEPA). 1992. NPDES
Stormwater Sampling Guidance Document. Office of Water. EPA/833/B-
92/001. July 1992.
United States Environmental Protection Agency (USEPA). 1993. EPA Quality
System Requirements for Environmental Programs (Draft) EPA/QA/R-1.
United States Environmental Protection Agency (USEPA). 1993. EPA
Requirements for Quality Assurance Project Plans for Environmental Data
Operations (Draft Final) EPA/QA/R-5.
United States Environmental Protection Agency (USEPA). 1993. Guidance for
Planning Data Collection in Support of Environmental Decision Making Using
the Data Quality Process. EPA/QA/G-4.
United States Environmental Protection Agency (USEPA). 1993. Guidance for
Conducting Environmental Data Assessments (Draft). EPA/QA/G-9.
United States Environmental Protection Agency (USEPA). 1993. Data Quality
Objective Process for Superfund-Interim Final Guidance. EPA/540/R-93/071.
United States Environmental Protection Agency (USEPA). 1993. Subsurface
Characterization and Monitoring Techniques. A Desk Reference Guide. Vols. 1
and 2. EPA/625/R-93/003a.
United States Environmental Protection Agency (USEPA). 1993. Use of
Airborne, Surface, and Borehole Geophysical Techniques at Contaminated Sites:
A Reference Guide. EPA/625/R-92/007.
2.8.6 Background
Dragun, J. and A. Chiasson. 1991. Elements in North American Soils.
Hazardous Materials Control Research Institute. Silver Spring, Maryland..
Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring.
Van Nostrand Reinhold: New York, New York, 320 pp.
Shacklette, HT; Boerngen, JG. 1984. "Element Concentrations in Soils and Other
Surficial Materials of the Conterminous United States." US Geological Survey.
USGS Professional Paper 1270.
Beckman, R. J., and R. D. Cook. 1983. Outliers. Technometrics 25:119-149.
2 - 73
USEPA. 1989. Statistical Analysis Of Groundwater Monitoring Data At RCRA
Facilities. EPA/350-SW/89-026.
USEPA. 1996a. Superfund Guidance For Evaluating The Attainment Of Cleanup
Standards. Volume 2. Groundwater. Center for Environmental Statistics.
Available HTTP: http://www.epa.gov/ces/pubs.html .
USEPA. 1996b. Soil Screening Guidance: Users Guide. Office of Solid Waste
and Emergency Response. Washington, DC 20460. EPA/540/R-96/018.
USEPA. 1996c. Superfund Guidance For Evaluating The Attainment Of
Cleanup Standards. Volume 1. Soils and Solid Media. Center for Environmental
Statistics. Available HTTP: http://www.epa.gov/ces/pubs.html .
2.8.7 Contaminants of Concern
United States Environmental Protection Agency (USEPA). 1989. Risk
Assessment Guidance for Superfund, Volume 1, Human Health Evaluation
Manual (Part A), Interim Final. Office of Emergency and Remedial Response
(Washington, DC). EPA/540/1-89/002. December.
United States Environmental Protection Agency (USEPA). 1992. Guidance for
Data Usability in Risk Assessment (Part A) Final. Office of Emergency and
Remedial Response (Washington, DC). Publication 9285.7-09A, PB92-963356.
April.
3 - 1
3.0 HUMAN HEALTH STANDARDS
3.1 Introduction
As described in the Voluntary Remediation and Redevelopment Rule (§60-3-9) the risk-
based standards provide for the protection of human health and the environment relative to
current and reasonably anticipated future land and water uses of the site. Risk-based standards
are used to determine whether a remedial response action is necessary to identify target cleanup
levels in the event that a remedial action is required, and to document that a level protective of
human health and the environment exists or has been achieved for a site.
This section describes the human health standards to be applied to voluntary remediation
sites consistent with §60-3-9 of the Rule. In conjunction with the ecological standards (Section
4.0 of this guidance), a variety of options may be applied to different contaminants at a site or to
different portions of a site. The goal is to provide flexible standards so that an applicant may
select the standard most appropriate for that particular site. The purpose of these standards is to
develop risk-based soil, sediment, surface water, and groundwater remedial objectives for site-
remediation.
Three options are available for developing risk-based human health standards at a site. A
De Minimis standard (§60-3-9.2 of the rule) consists of pre-established numerical values from
look-up tables (table 60-3B of the rule and Appendix C of this guidance). A Uniform Risk-
Based Standard (§60-3-9.3 of the Rule) is determined by using established risk equations that
incorporate either default or site-specific values for variable (formulae and default values are
provided in Appendix D of this guidance). A Site-Specific Risk-Based Standard (§60-3-9.4 of
the Rule) uses baseline and/or residual risk assessment to establish protective cleanup standards
based on site-specific conditions and reasonably anticipated future land and water uses. As
specified in the Rule (§60-3-9), where background levels of contaminants exceed the risk-based
levels, background levels may be used as cleanup standards (see Subsection 2.5 and Appendix B
of this guidance for procedures to determine background).
Section §60-3-8 of the Rule provides risk protocols for conducting baseline human health
and ecological risk assessments, and for residual risk assessments (described in Section 5 of this
guidance) of conditions following implementation of the proposed remedy. Procedures for
probabilistic assessments are also addressed in §60-3-8 of the Rule and Section 6 and Appendix I
of this guidance.
Figure 3-1 provides a flow diagram that illustrates the decision-making process for
selecting a method of deriving human health standards for a site. This diagram should be used
together with the Checklist for Determination of the Applicable Standard (Appendix C-1). This
decision-making process should begin only after a conceptual site model has been developed
(see Subsection 2.2.4 of this guidance) COCs have been identified (see Subsection 2.6 of this
guidance for methods of COC selection), and sufficient data collected to characterize COC
concentrations in media of concern. Subsection 2.3.1 of this guidance describes additional data
requirements for risk assessment.
3 - 2
FIGURE 3-1: HUMAN HEALTH REMEDIATION STANDARD SELECTION PROCESS
Refine Conceptual
Site Model
(see Figure 2-1)
Include in Final Report
Concentration
of COCs
< DeMinimis Standard
Clean-up to Either Human
Health DeMinimis, Standard or
Ecological Standard Whichever
is Lower (1)(2)
Further Evaluate Using
Uniform Risk-Based Standard
Concentration of COCs
< Uniform Standard
Clean-up to Either Human Health Uniform Standard
or Ecological Standard
Whichever is Lower (1)(2)
Further Evaluate Using Site-Specific
Risk Based Standard
Concentration s of COCs
<Standard
Site-Specific
Clean-up to Either Human Health Uniform Standard
or Site Specific Cleanup Standard
Within Appropriate Risk Range (1)(2)
(1) Prior to clean up the applicant must evaluate the remedial alternatives, submit a
Remedial Action Plan, and obtain WVDEP approval of the plan.
(2) Assumes background has been determined (see Subsection 2.5) (3) Ecological receptors are not a factor or ecological standards are > Human Health Standards
No
Yes(3)
Yes(3)
No
Yes(3)
No
3 - 3
For many simple sites with few contaminants, the De Minimis Standards may be
sufficient to determine the need for remediation. For more complex site (e.g., sites where
leaching of chemicals from soil to groundwater is a concern or sites where surface water has
been impacted), or sites having contaminants which should not be included in the De Minimis
evaluation (e.g., volatile chemicals in soil), the Uniform Risk-Based or Site-Specific Risk-Based
Standards must be applied to all or portions of the site. Where site contamination is impacting
surface waters, the following must be addressed:
The De Minimis standard may not be used for any contaminant at a site where
that contaminant is impacting surface water;
The uniform and site-specific remediation standards for surface water are the
applicable water quality standards found at 46CSR1 (surface water quality
standards promulgated by the Environment Quality Board):
An applicant may demonstrate compliance with surface water quality
standards where site contamination is originating from a non-point source by
following the Office of Water Resources’ “Monitoring Procedures to
Determine Impact of Surface Water from Non-Point Source Site Remediation
Projects.” (see Appendix J). The foregoing demonstration does not relieve the
applicant of the requirement to assure that the adopted remediation standard is
protective of human health and ecological receptors of concern.
For any contaminants for which there is no water quality standard in 46CSR1,
a remediation standard may be developed using the methodology for
determining a site-specific standard in Section 3.4 of this guidance.
Subsection 1.1.3 of this guidance describes the options for selecting human health and
ecological standards for a site. The following subsections provide more detailed guidance for
using or developing human health standards.
3.2 Human Health De Minimis Risk-Based Standard
The De Minimis Standard is designed to be the quickest and easiest method from which
remediation standards and objectives are derived, which also being protective of human health.
As described in §60-4-9.2 of the Rule, the De Minimis standards apply to chemicals for which
the primary exposure routes will be ingestion from soil, or ingestion. For soil, the De Minimis
Standard will be either the risk-based concentrations (RBCs) (found in Table 60-3B of the Rule
and reproduced in Appendix C-1 of this guidance) or the natural background levels of the
contaminant, whichever is higher. RBC standards are provided in Appendix C for both
residential and industrial land use scenarios. For groundwater, the De Minimis Standard will be
the higher of the two, either the value from Appendix C or the natural background concentration.
No De Minimis Standards are available for surface water or sediments, and De Minimis
Standards should not be applied to volatile organic chemicals (denoted in Appendix C by an “X”
in the VOC column) in soils, or to chemicals that may have a primary route of exposure other
than ingestion (e.g., inhalation after particulate release to air). Thus, development of an accurate
3 - 4
conceptual site model, as described in Subsection 2.2.4 of this guidance, is a critical step in
determining eligibility of a site, or portions of a site for assessment using De Minimis Standards.
Site eligibility for using the De Minimis Standards is determined by responses to the checklist
for determining the appropriate standard included in Appendix C-1 of this guidance.
3.2.1 De Minimis Standards for Soil
The De Minimis Standard for both surface (<2 feet depth) and subsurface (>2 feet depth)
soils is the higher of the following values:
RBCs listed in Table 60-3B of the Rule and reproduced in Appendix C (for
residential or industrial, as appropriate)
Natural background levels (Subsection 2.5)
The De Minimis Standard may be selected for all or a portion of the contaminants and for
all or a portion of the site, as appropriate. A land use convenant restricting residential land uses
is required for portions of a site where the industrial De Minimis Standards are used.
Background concentrations of naturally-occurring constituents vary greatly depending
upon the source of the soil matrix or depositional environment. When natural background is
used as the De Minimis Standard, attainment may be demonstrated in several ways. A simple
approach is to document that individual sample concentrations for a particular contaminant from
a site are less than the upper tolerance limits (UTL) for that same analytes in natural background
samples. Methods for calculating the UTL are provided in Appendix B. A comparison of the
UTLs for analytes in natural background soils to the De Minimis Standards provided in Table
60-3B of the Rule indicates that natural background concentrations of arsenic, beryllium, iron,
and may be greater than the De Minimis Residential Standards for those analytes. It is not
practical to remediate a site to a standard less than background.
3.2.2 De Minimis Standards for Ground Water
The De Minimis Standard for ground water is the highest value of the following:
Groundwater contaminant concentration limits established in Title 46 – Series
12 of the code of State Rules (46CSR12) (included in table 60-3B of the Rule
and Appendix C of this guidance).
RBC lookup values from Table 60-3B of the Rule and reproduced in
Appendix C of this guidance.
Natural background values for inorganics (see Subsection 2.5 and Appendix
B).
3 - 5
3.2.3 Implementing the De Minimis Standards
For soils, after concentrations of COCs are determined, the values are compared to the
RBC for residential or industrial land uses, as appropriate. If the 95th
percentile upper
confidence limit (UCL) on the mean (see Subsection 2.5 and Appendix B) or the maximum value
of each COC is below the RBC value and ecological receptors are not of concern, then no further
site assessment or remediation needs to occur (see Figure 3-1). If the natural background level
exceeds the RBC value, the background level may be used as the standard. If the contaminant
concentrations exceed both levels, the applicant has the option of reducing the contaminant
concentrations to the higher of the background or RBC value, or determining an alternative
remediation standard using the Uniform or Site-Specific Standards (Subsections 3.3 or 3.4 of this
guidance). Sample locations that are clearly part of a different population should be evaluated
separately (see Gilbert Appendix B – has statistical methods for 1987 determining outliers).
For groundwater, if COCs in each monitoring well are below the values listed in
Appendix C, then no further assessment is necessary. If some inorganics exceed the RBCs but
have the potential to be within background, then background groundwater concentrations should
be evaluated using the procedures outlined in Subsection 2.5 and Appendix B. If background
concentrations are higher than the RBC, background may be used for the standard. As with
soils, if contaminant levels exceed RBCs or background, the applicant has the option of cleaning
up to the De Minimis Standard or further evaluating the site using either the Uniform or Site-
Specific Standard.
The De Minimis Standard may not be used for any contaminant at a site where the
contaminant is impacting surface water.
3.3 Uniform Risk-Based Standard
The Uniform Risk-Based Standard described in §60-3-9.3 of the Rule relies on uniform,
approved methodologies, exposure factors, and other input variables to calculate remediation
standards. Site-specific variables may replace default variables with adequate technical
justification. The remediation standards will be protective of human health based on current or
reasonably anticipated future land and water use. Applicants who select the Uniform Standard
need not meet the De Minimis Standard.
USEPA (1991a, 1996b,c) has developed standard default risk equations for typical
exposure pathways; it is those exposure pathways that are considered in the Uniform Standard.
The equations used in the Uniform Standard consider the following residential exposure
pathways:
Ingestion from drinking groundwater
Ingestion from drinking surface water
Inhalation of volatile from groundwater
Inhalation of volatiles from surface water
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Ingestion of soil
Inhalation of volatiles and particulates from soil
Soil concentrations protective of groundwater
The equations used in the Uniform Standard considers the following industrial exposure
pathways:
Ingestion of soil
Inhalation of volatiles and particulates from soil
For any land use, soil concentrations that are protective of groundwater must also be
determined. Any major exposure pathways that were not listed (e.g., ingestion of water during
recreational use of a surface water body) for this standard may need to be evaluated under the
Site-Specific Standard.
The default assumptions and equations used to determine values for remediation levels
under the Uniform Standard are found in Appendix D of this guidance. Site-specific information
may be substituted for any of the default values listed provided that the justification for the site-
specific value is adequately documented. Where significant risks occur from more than one
pathway, cleanup levels determined from the Uniform equations should be adjusted to consider
cumulative risks. It should be noted that the Uniform Risk-Based Standard equations in
Appendix D are not appropriate for lead. Lead in drinking water must meet the WV
Groundwater Standard. Lead in soils must meet either the De Minimis Standards or the method
for deriving lead standards presented in Appendix F of this guidance may be used to derive a
cleanup value.
As with the De Minimis Standard, not all sites may be appropriate for evaluation using
the Uniform Standard approach. For example, Uniform Standard methods for assessment of
contaminated sediments are not provided. An accurate conceptual site model is crucial in
determining whether Uniform Standards will be sufficient to guide remediation decisions at a
site (see Subsection 2.2.4 of this guidance for a description of conceptual site model
development).
3.3.1 Uniform Standards for Groundwater
The Uniform Standard for groundwater includes consideration of inhalation and ingestion
of groundwater. For sites where the groundwater is potable, the Uniform Standard is not likely
to differ from the De Minimis Standards that are described in Subsection 3.2.2 of this guidance.
The standard applied at such sites would be the higher of the MCL, the risk-based uniform
standard based on ingestion exposures (see Appendix D), or the natural or anthropogenic
background concentration for each COC.
For sites where chemical contaminants are present in groundwater, the methods described
in Appendix D of this guidance should be used to derive a risk-based Uniform Standard.
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For sites where potability or groundwater use may be an issue, §60-3-9.3.c of the Rule
states that the Uniform Standard for groundwater shall be derived based on current or reasonably
anticipated future land and water uses, the potential for migration of contaminants, and the
usefulness of the aquifer as a source of drinking water. Groundwater that has a background total
dissolved solids content greater than 2500 milligrams per liter (mg/L) is probably not useful as a
source of drinking water. If it is suitably demonstrated that the groundwater is not and cannot
serve as a source of drinking water and that the aquifer is not hydrogeologically connected to an
aquifer being used for drinking water, the groundwater is not suitable as a source of drinking
water.
3.3.2 Uniform Standards for Soil
The Uniform Standards for soil are based on USEPA’s soil screening guidance (USEPA
1996b and c). In the soil screening guidance, screening levels are provided for two exposure
routes, ingestion and inhalation. For volatile chemicals inhalation of vapors is considered, while
for nonvolatile chemicals inhalation of particulates is included. The methods described in
Appendix D of this guidance should be used to derive a risk-based Uniform Standard that
accounts for exposures occurring by both ingestion and inhalation. Site-specific adjustments
may include consideration of site data regarding the relative oral bioavailability of chemicals in
soil (see Appendix E of this guidance), site data pertaining to the flux rates of volatile chemicals
from soil, or site or regional data modifying assumptions about particulate releases to air.
The soil screening guidance also includes screening levels that provide varying degrees
of protection for migration of chemicals from soil to groundwater. Two sets of values are
provided based on dilution and attenuation factors (DAFs) of 20 and 1. Site specific DAFs may
be developed with appropriate documentation. The standards for soil concentrations that are
protective of groundwater were derived by USEPA using a complex model to predict
contaminant migration from soil to groundwater in a two stage process: 1) release of
contaminant in soil leachate; and 2) transport of the contaminant through the underlying soil and
aquifer to a receptor well. The USEPA methodology is described in detail in Soil Screening
Guidance: Technical Background Document (USEPA, 1996b). The USEPA document also
provides guidance for making site-specific adjustments to the default standards.
In cases where risk-based or groundwater protection Uniform Standards are exceeded by
anthropogenic background concentrations, the background value may be used to determine the
need for remediation.
3.3.3 Establishing the Uniform Standards
For known or suspected carcinogens, acceptable clean-up levels may be established using
Uniform Standards established at levels that represent an excess upper bound lifetime risk of
between one in ten thousand (1 x 10-4
) to one in one million (1 x 10-6
). Special notification must
be given for those non-brownfield sites where remediation levels will exceed the one in one
hundred thousand (1 x 10-5
) level of risk for industrial sites and the 1 x 10-6
risk for residential
sites (§60-3-9.3.d of the Rule). Risks should be characterized by the quantification of
cumulative risks posed by multiple contaminants. For cumulative site risk, the cumulative site
risk shall not exceed one in ten thousand (1 x 10-4
) (§60-3-9.3.g of the Rule).
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For individual systemic toxicants, the Uniform Standards shall represent levels to which
the human population could be exposed without appreciable risk of deleterious effect. For the
Uniform Standard, the hazard quotient (HQ) shall not exceed one (1.0) for any individual or
group of toxicants that act on the same target organ (§60-3-9.3.e of the Rule). Where multiple
systemic toxicants affect the same target organ or act by the same method of toxicity, the Hazard
Index (sum of the hazard quotients) shall not exceed 1.0. Where multiple systemic toxicants do
not affect the same organ, the hazard index shall not exceed 10.0 (§60-3-9.4.b of the Rule). If
the Hazard Index exceeds 1.0, further evaluations may be necessary as discussed in Section
3.4.1.3, Approach for Calculating NonCancer Risks. Consult the Integrated Risk Information
System (IRIS) (www.epa.gov/ngispgm3/iris) or Health Effects Assessment Summary tables
(HEAST) databases for the most recent information on target organs/systems affected by various
chemicals.
If a contaminant exhibits both carcinogenic and noncarcinogenic effects, then the more
conservative risk-based standard (i.e. the lower of the two values) shall be used as the
remediation standard (§60-3-9.2e of the Rule).
Either natural or anthropogenic background concentrations may be used as the Uniform
Standard. Background concentrations of anthropogenic constituents vary greatly depending
upon regional sources and local conditions. The most critical consideration in developing an
anthropogenic background will be to demonstrate that the anthropogenic levels found are from
area-wide sources not related to site activities. Methods for determining background are
provided in Subsection 2.5 and Appendix B of this guidance.
3.3.4 Uncertainty Analysis
It is important to specify the uncertainties associated with the assumptions made in
developing the Uniform Standard to put the standard in proper perspective. Highly quantitative
statistical uncertainty analysis is usually not practical or necessary. As in all environmental risk
assessments, it is already known that uncertainty about the numerical results are generally large
(i.e., on the range of an order of magnitude or greater). Consequently, it is more important to
identify the key site-related variables and assumptions that contribute most to the uncertainty
than precisely quantify the degree of uncertainty in the risk assessment (USEPA, 1989). USEPA
(1989) suggests a format for qualitatively identifying uncertainty associated with risk
calculations (see Exhibit 6-21, USEPA, 1989) which should be adequate for evaluating
uncertainties associated with development of the Uniform Standard.
3.3.5 Attaining Compliance with the Uniform Standard
3.3.5.1 Soils
For soils, compliance with the Uniform Risk-Based Standards, or with the background
level that has been equated to any of the standards, is achieved when a measure of the average
contaminant concentration on the site or in the exposure unit is equal to or less than the standard.
A measure of the average contaminant concentration is the appropriate value to compare to the
standards because risk-based standards represent averages themselves (see USEPA 1996b).
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Because average concentrations are uncertain, the 95% UCL on the mean concentration
should be calculated for all soil samples within the site or exposure unit. The UCL can be
calculated following the procedure given in USEPA (1992a). The UCL, which provides a
measure of the average concentration that accounts for its uncertainty, is compared to the
standard. If the UCL is less than the standard, then remediation is complete. Note that this
procedure does not require each sample location on the site to have a contaminant concentration
less than the standard. From a risk basis, it is only necessary for the average contaminant
concentration to be less than the standard. Sample locations that are clearly part of a different
population should be evaluated separately (see guidance such as USEPA, 1996a).
3.3.5.2 Groundwater
Because of the site-specific factors related to groundwater, there are several methods that
can be used to demonstrate compliance with the Uniform Standard. Approvable compliance
demonstrations include comparison of highest level in any well to the standard, statistical
comparison of results from select wells to the standard, or other reasonable methods as approved
by the Director. When an acceptable demonstration is made that site levels are below the
Uniform risk-based standard, the applicant has attained compliance and no additional
remediation will be required.
The following is a list of factors to consider when deciding upon the method to be used to
demonstrate compliance:
In most situations, it is recommended that a statistical evaluation of the
groundwater be conducted. An approved and acceptable method is to
calculate a one-sided 95% upper confidence level on the mean on selected
wells.
Selection of wells to be used is supported by the site characterization and any
relevant risk assessment. The wells must be part of the same population (e.g.,
wells within a plume of contamination).
If there is an insufficient number of wells (or samples) to do statistical
evaluation, then the results from each well may need to be compared to the
standard. In this case, all results would need to be below the standard to
demonstrate compliance. It should be noted that the applicant has the right to
install additional wells to be able to do a statistical evaluation.
If areas of contamination (i.e. plume) exist that are at least an order of
magnitude higher than surrounding concentrations, those may need to be
evaluated separately.
The applicant may use other statistical methods or evaluated techniques
provided they are shown to be appropriate and adequate and are approved by
the Director.
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3.4 Site-Specific Risk-Based Standard
The Site-Specific Standard (described in §60-3-9.4 of the Rule) relies on a baseline or
residual risk assessment conducted by the applicant, as described in §60-3-8.4 of the Rule. All
sites or portions of sites qualify for the Site-Specific Standard, but some sites may be more easily
or economically remediated using De Minimis or Uniform Standard methods. Site-specific
remediation standards must take into account current and reasonably anticipated future land and
water use expectations and the use of institutional or engineering controls, if applicable.
Critical review of the site conceptual model is the first step in determining whether a
baseline risk assessment needs to be conducted. As described in Subsection 2.2.4 of this
guidance, the site conceptual model describes potential receptors and potentially complete
exposure pathways. The complexity of the conceptual model, i.e., the kinds of affected media,
number of complete exposure pathways, and exposure scenarios will determine the need for a
baseline risk assessment. At this stage the conceptual site model, list of complete exposure
pathways, and list of COCs should be reviewed to determine if any revisions are needed based
on currently available information.
Prior to undertaking a baseline risk assessment, the adequacy of available data to support
a risk assessment should be determined. Data requirements for risk assessment are listed in
Subsection 2.3.1 of this guidance. Guidance on developing data quality objectives (DQOs) for
risk assessment purposes may be found in Guidance for Data Usability in Risk Assessment (Part
A) Final (USEPA, 1992b). Particular attention should be paid to whether DQOs have been met
(see Subsection 2.4.1 of this guidance). DQOs from the site assessment should be reviewed and
refined for the risk assessment process.
The following subsections provide guidance for conducting the baseline risk assessment,
followed by guidance for implementing the Site-Specific Standard. For point estimates, more
detailed guidance is provided in Appendix H. Probabilistic risk assessments are discussed in
Appendix I.
3.4.1 Baseline Risk Assessment
The guidance provided in this subsection may be applied to both baseline risk assessment
and to residual risk assessments. The primary source of guidance for the conduct of baseline risk
assessments is found in the Risk Assessment Guidance for Superfund: Volume I – Human
Health Evaluation Manual (Part A) (USEPA, 1989). When evaluating risks of exposure to lead,
USEPA’s childhood lead exposure model should be used for residential land uses or other land
uses where young children may be exposed frequently. For industrial / commercial land uses,
USEPA’s adult lead exposure model should be used. Alternative models with appropriate
documentation may be used for evaluating lead exposures to adults with the approval of the
Director. Lead risk assessment guidance is provided in Appendix F of this document. The
methods described in the following subsections do not apply to evaluating contamination by
radionuclides. Until specific guidance is issued by WVDEP, evaluation of radionuclide
contamination should be conducted in accordance with current USEPA guidance.
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3.4.1.1 Exposure Assessment
The objective of the exposure assessment is to estimate the type and magnitude of
exposures to the chemicals of potential concern that are present at or migrating from a site.
Exposure assessments are conducted to estimate the magnitude of potential human exposures,
the frequency and duration of these exposures and the pathways by which humans are potentially
exposed. Exposures are quantified only for complete exposure pathways. A complete exposure
pathway includes four elements:
A source of a chemical (s)
A mechanism of release, retention or transport of a chemical in a given
medium (e.g., air, water, soil)
A point of human contact with the exposure medium (i.e., exposure point) and
A route of exposure at the point of contact (i.e., ingestion, inhalation or
dermal contact).
Without the potential for all of these elements, an exposure pathway is not complete and
does not need to be quantified.
For complete exposure pathways, reasonable maximum exposure (RME) estimates for
both current and future land-use assumptions are to be determined. Current exposure estimates
are used to determine whether a threat exists based on existing exposure conditions at the site.
Future exposure estimates are used to provide decision-makers with an understanding of
potential future exposures and threats under reasonably anticipated future land and water uses.
Future exposure assessments include a qualitative estimate of the likelihood of such exposures
occurring. In addition to deterministic estimates of the RME, probabilistic exposure estimates
may be conducted in accordance with §60-3-8.7 of the Rule and Section 6 and Appendix I of this
guidance to better quantify uncertainty and assist in risk management decisions at the site.
An exposure assessment involves a broad three-step process:
STEP 1: Characterizing Exposure Setting
Analyzing physical setting (climate, vegetation, groundwater hydrology,
surface water, soil type, etc.)
Identifying exposed and potentially exposed populations (from site visit,
population surveys, topographic, housing or other maps, etc.) For such things
as location relative to the site, activity patterns, and the presence of sensitive
subpopulations.
Determining current land use and reasonably anticipated future land use (and
current and future population characteristics)
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STEP 2: Identifying Exposure Pathways
Estimating chemical sources, releases and receiving media
Identifying all complete pathways of exposure. Each exposure pathway
describes a unique mechanism by which a population may be exposed.
Identifying COCs for each medium
Evaluating fate and transport in release media (i.e., accumulation,
transformation, transport, etc.)
STEP 3: Quantifying Pathway-Specific Exposure (based upon exposure concentrations
and intake variables)
Estimate the exposure concentrations separately for groundwater, surface
water, sediments, soil, food, and air, as appropriate. Because of the
uncertainty associated with any estimate of exposure concentration, the upper
confidence limit (the 95% upper confidence limit) on the arithmetic average
will be used for this variable. It is necessary to verify whether the data is
normal or log normal and calculate the UCLS accordingly, using the
procedures outlined in Appendix B.
Estimating contaminant intakes for each exposure route for each complete
pathway.
Most of Steps 1 and 2 will be completed during development of the site conceptual
model, and will be reviewed and updated as the exposure assessment is started. Step 3 will be
the most time consuming aspect of the exposure assessment. Exposure is defined as the contact
of a human with a chemical contaminant. The magnitude of the exposure is determined by
measuring or estimating the intake or dose of the contaminant in milligrams (mg) of chemical
per kilogram body weight (kg). These intake estimates require site-specific data on chemical
concentrations that people are likely to encounter to be combined with estimates of intake rates
for the medium the chemical is in, e.g., the amount of soil ingested by a child each day. The
generic formula for determining contaminant intakes follows:
Equation 3-1:
Intake (mg/kg body weight-day) = C * CR * EFD * 1/AT
BW
Where:
C = chemical concentration (e.g., mg/L water)
CR = contact rate with the medium containing the chemical
(e.g., L/day)
EFD = exposure frequency (days per year) and duration (years)
(EF * ED yields days for units)
BW = body weight (kg) – 70 kg
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AT = averaging time (days) – (e.g., 70 yr for carcinogens,
30 yr for noncarcinogens)
The intakes that may need to be determined include, but are not limited to:
Intake from drinking ground and/or surface water
Intake from incidental ingestion of surface waters while swimming
Intake from dermal contact with ground and/or surface water
Incidental ingestion of soil, sediment and/or dust
Dermal intake of soil, sediment and/or dust
Intake through inhalation of vapor-phase chemicals
Intake through inhalation of particulate phase chemicals
Intake through foods
Detailed formulas and assumptions for calculating exposure by many of these pathways
is provided in Appendix D. USEPA has issued numerous documents providing guidance and
data for use in exposure assessments. These documents are the preferred sources of methods and
assumptions to be used by the applicant in site-specific risk assessments.
United States Environmental Protection Agency (USEPA). 1989. Risk
Assessment Guidance for Superfund: Volume I- Human Health Evaluation
Manual (Part A). Office of Emergency and Remedial Response. EPA/540/1-
89/002.
United States Environmental Protection Agency (USEPA). 1991a. Risk
Assessment Guidance for Superfund: Volume I - Human Health Evaluation
Manual (Part B, Development of Risk-Based Preliminary Remediation Goals)
Interim. Office of Emergency and Remedial Response. Publication 92585.7-
01B. December.
United States Environmental Protection Agency (USEPA). 1992c. Dermal
Exposure Assessment: Principles and Applications. Office of Research and
Development, Washington, DC. EPA/600/8-91/011B.
United States Environmental Protection Agency (USEPA). 1991b. Standard
Default Exposure Factors for Superfund. Office of Emergency and Remedial
Response. OSWER Directive 9285.6-03.
A massive compilation of data for use in exposure assessment can be found in USEPA’s
Exposure Factors Handbook. The August 1997 version is available on-line at
http://www.epa.gov/ordntrnt/ORD/WebPubs/exposure/index.html. Adobe Acrobat reader is
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needed to read these PDF documents. The USEPA web site should be checked for availability of
more recent versions.
United States Environmental Protection Agency (USEPA). 1997. Exposure
Factors Handbook. Volume I-General Factors. EPA/600/P-95/002Ba.
United States Environmental Protection Agency (USEPA). 1997. Exposure
Factors Handbook. Volume II-Food Ingestion Factors. EPA/600/P-95/002Bb.
United States Environmental Protection Agency (USEPA). 1997. Exposure
Factors Handbook. Volume III-Activity Factors. EPA/600/P-95/002Bc.
When estimating ingestion intakes, it may be appropriate to adjust the intake estimate to
account for different degrees of absorption from different exposure media. The need for such an
adjustment arises when the exposure medium differs from the exposure medium in toxicity
studies relied on for the toxicity assessment (see Subsection 3.4.1.2 of this guidance). Such
adjustments are most commonly performed to account for reduced absorption of chemicals from
soil compared to absorption of dissolved chemical administered in water. Detailed guidance for
making relative bioavailability adjustments is provided in Appendix E of this document.
Exposure assessments for contaminants where significant risk is contributed via food
ingestion should consider uptake from soil into plants or uptake into fish, as appropriate.
Contaminants such as certain organic mercury compounds or organic compounds with a high
octanol-water partition coefficient may exhibit dramatic increases in concentration in seafood;
thus, the food ingestion pathway may dominate risk estimates. Where subsistence hunting and
fishing represent a significant part of the diet of subpopulations, appropriate biomagnification
factors should be incorporated into risk equations.
Summary of Exposure Information Needed
Estimated intakes (chronic, subchronic, and short-term, as appropriate) for each
contaminant of concern
Important exposure modeling assumptions, including:
- contaminant concentrations at exposure points
- frequency and duration of exposure
- absorption assumptions (bioavailability, etc.)
- characterization of uncertainties
List which exposure pathways can reasonably contribute to the exposure of the same
individuals over the same time period.
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Uncertainties Related to Exposure Assessment
The exposure assessment should conclude with a discussion of sources of uncertainty in the
estimate. Common sources of uncertainty include:
Adequacy and completeness of the sampling data (e.g., how well the data
represents actual site conditions, or whether or not all COCs have been identified)
Identification of all potential exposure pathways and routes of exposure
Accuracy of exposure assumptions (i.e., how well assumptions reflect actual
exposure conditions).
The nature and likely magnitude of effect of each source of uncertainty on exposure
estimates should be discussed.
3.4.1.2 Toxicity Assessment
The purpose of a toxicity assessment is to evaluate the potential for substances of
potential concern to cause adverse health effects in exposed persons and to define, as thoroughly
as possible, the relationship between the extent of exposure to a hazardous substance and the
likelihood and severity of any adverse health effects. Standard procedures for a toxicity
assessment include identifying toxicity values for carcinogenic and noncarcinogenic effects and
summarizing other relevant toxicity information. WVDEP relies on toxicity values, developed
and verified by USEPA, to describe the dose-response relationship. If verified toxicity values for
a COC are not available from USEPA, the applicant should consult with WVDEP prior to
relying on other sources of toxicity values. Complete copies of all references used to support
alternate toxicity values must be provided to WVDEP upon request.
USEPA-derived toxicity values used in risk assessments are termed carcinogenic slope
factors (CSFs), reference doses (RfDs), and reference concentrations (RfCs). Oral slope factors
are used to estimate the incremental lifetime risk of developing cancer corresponding to ingested
doses calculated in the exposure assessment. Some chemicals also have inhalation slope factors
that are used to assess inhaled chemicals. The potential for noncarcinogenic health effects of
ingested chemicals is typically evaluated by comparing estimated daily intakes with RfDs, which
represent daily intakes at which no adverse effects are expected to occur over a lifetime of
exposure. Both CSFs and RfDs are specific to the route of exposure (e.g., ingestion [oral]
exposure).
Currently, there are no CSFs or RfDs for dermal exposure; therefore, route-to-route
extrapolation is necessary to assess dermal exposure. This process is described in Appendix E.
No toxicity values are available for lead. Instead, USEPA relies on benchmark values for blood
lead levels that are health protective. Exposures are assessed by comparing the blood lead
benchmark values with blood lead levels predicted by pharmacokinetic models that estimate
blood lead levels resulting from specified doses of lead. These models are described in
Appendix F of this guidance.
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The primary source for USEPA-derived toxicity values is USEPA’s IRIS data base. This
computerized database contains verified toxicity values in addition to up-to-date health risk and
USEPA regulatory information for many substances commonly detected at hazardous waste
sites. USEPA’s Health Effects Assessment Summary Tables (USEPA 1993) also provide
USEPA-derived toxicity values that may or may not be verified at the time of publication.
Because toxicity information may change rapidly and quickly become outdated, care
should be taken to find the most recent information available. IRIS is updated monthly, provides
verified RfDs and slope factors, and is the USEPA’s preferred source of toxicity information.
Information in IRIS supersedes all other sources. Only if values are unavailable in IRIS for the
contaminant of concern should other information sources be consulted. Toxicity values which
have been withdrawn from IRIS may be used in the risk assessment provided a discussion is
included on the uncertainty associated with using these values. The USEPA web server has
published the updated IRIS list. It is available at: http://www.epa.gov/ngispgm3/iris/Substance_List.html
or call the IRIS User Support at (513) 569-7254.
Toxicity Information Needed
For each COC included in the risk assessment, a toxicity profile or a tabular
representation of the information should be provided that includes the following elements:
carcinogenicity of the chemical (e.g., oral and/or inhalation slope factors
verified by USEPA, critical study(ies) upon which the slope factors are based
(including the exposure/dosing medium), weight of evidence and
carcinogenicity classification, and type of cancer observed for all Class A
carcinogens)
systemic toxicity of the chemical, (e.g., chronic and subchronic RfDs and
RfCs, the critical effect associated with each RfD and RfC (e.g., kidney
damage). critical study(ies) upon which the RfD and/or RfC is based
(including the exposure/dosing medium), uncertainty factors and modifying
factors used in deriving each RfD/RfC, and “degree” of confidence in each
RfD (i.e., high, medium, or low))
pharmacokinetic data that may affect the extrapolation from animals to humans
for both the RfD and the slope factor
the degree of absorption from various media
uncertainties in any route-to-route extrapolations
Sample table needed.
For a more detailed evaluation of the toxicity of a compound, ATSDR profiles may be
included in an appendix.
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Noncarcinogenic Assessment
Currently USEPA derives RfDs by applying uncertainty factors to a no observed adverse
effect level (NOAEL) or from a lowest observed adverse effect level (LOAEL) for each
chemical. Another method of deriving RfDs is called the benchmark dose (BMD) approach
(USEPA, 1995). The BMD is a dose of a chemical that is predicted to result in a specified
amount of increased response compared to unexposed controls. In the BMD approach a dose-
response model is applied to toxicity data. Toxicity information used to IRIS to derive BMDs
should be obtained from the IRIS database, if available. A statistical lower bound on the BMD
(termed the BMDL) may be used as a substitute for the traditional NOAEL or LOAEL method of
deriving RfDs.
Inhalation RfCs
The inhalation RfC is analogous to the oral RfD and is likewise based on the assumption
that thresholds exist for certain toxic effects. The inhalation RfC considers toxic effects for both
the respiratory system (portal-of-entry) and for effects peripheral to the respiratory system
(extrarespiratory effects). It is expressed in units of mg/cu.m. In general, the RfC is an estimate
(with uncertainty spanning perhaps an order of magnitude) of a daily inhalation exposure of the
human population (including sensitive subgroups) that is likely to be without an appreciable risk
of deleterious effects during a lifetime. Methods for deriving RfCs can be found in Interim
Methods for Development of Inhalation Reference Doses (USEPA, 1990) and Methods for
Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry
(USEPA, 1994a)
Carcinogenicity Assessment
The carcinogenic assessment includes three aspects for the substance in question; the
weight-of-evidence judgment of the likelihood that the substance is a human carcinogen, and
quantitative estimates of risk from oral exposure and from inhalation exposure. The quantitative
risk estimates are presented in three ways. The slope factor is the result of application of a low-
dose extrapolation procedure and is presented in milligrams per kilogram-day [mg/kg-day]-1
.
The unit risk is the quantitative estimate in terms of either risk per micrograms per liter (g/L)
drinking water or risk per micrograms per cubic meter (g/m3)
air breathed. The third form in
which risk is presented is a drinking water or air concentration providing cancer risks of 1 in
10,000, 1 in 100,000 or 1 in 1,000,000. The rationale and methods used by USEPA to develop
the carcinogenicity information in IRIS are described in The Risk Assessment Guidelines of
1986 (EPA/600/8-87/045) and in the IRIS Background Document. IRIS summaries developed
since the publication of USEPA's more recent Proposed Guidelines for Carcinogen Risk
Assessment also utilize those guidelines where indicated (Federal Register 61(79):17960-18011,
April 23, 1996.
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Uncertainties Related to Toxicity Assessment
Sources of uncertainty in the toxicity assessment should be identified. Typical sources of
uncertainty include:
Using dose-response information from effects observed at high doses to predict
the adverse health effects that may occur following exposure to the low levels
expected from human contact with the agent in the environment
Using dose-response information from short-term exposure studies to predict
the effects of long-term exposures, and vice-versa
Using dose-response information from animal studies to predict effects in
humans
Using dose-response information from homogeneous animal populations or
healthy human populations to predict the effects likely to be observed in the
general population consisting of individuals with a wide range of sensitivities
The likelihood and relative magnitude of each source of uncertainty should be discussed.
For example, USEPA states that the range of possible values around RfDs is “perhaps an order
of magnitude” (USEPA, 1995).
3.4.1.3 Risk Characterization
Risk characterization is the final step of the baseline human health risk assessment
process. In this step the exposure and toxicity assessments are integrated into quantitative and
qualitative expressions of risk. To characterize the potential noncarcinogenic effects of ingested
chemicals, comparisons are made between projected intakes of contaminants and RfDs. For
inhalation exposures, exposure point concentrations in air may be directly compared to the RfC.
To characterize the potential carcinogenic effects, the probabilities that an individual will
develop cancer over a lifetime of exposure are estimated from projected intakes and CSFs. The
major assumptions, scientific judgments, and the uncertainties embodied in the risk assessment
should also be presented.
Cancer and noncancer health risks are estimated, assuming long-term exposure to
chemicals detected at the site. The risk characterization methods described in USEPA guidance
(USEPA 1989) are used to calculate upper-bound excess lifetime cancer risks for potential
carcinogens and hazard indices for chemicals with noncancer health effects. Following USEPA
guidance, numerical estimates of risk should be rounded to one significant figure to reflect the
level of certainty associated with calculated risks. Risks associated with exposures to lead may
be assessed following the methods described in Appendix F.
Risk characterizations are completed in the following broad steps:
3 - 19
STEP 1: Organize Outputs of Exposure and Toxicity Assessments
Exposure duration
Absorption adjustments
Consistency check
STEP 2: Quantify Pathway Risks for Each Substance
Estimate cancer risk for each contaminant
Estimate the Noncancer HQ for each contaminant
Calculate total cancer risk for each exposure pathway
Calculate noncancer HI for each exposure pathway
STEP 3: Combine Risks Across Pathways that affect the same individual(s) over the
same time periods:
Sum Cancer Risks
Sum Hazard Indices
STEP 4: Assess and Present Uncertainty
Site-specific factors
Toxicity assessment factors
STEP 5: Consider Site-Specific Human Health or Exposure Studies
Compare adequate studies with results of risk assessment
STEP 6: Summarize Results of the Baseline Risk Assessment
Approach for Calculating Cancer Risks
Quantifying total excess cancer risk requires calculating risks associated with exposure to
individual carcinogens and aggregating risks associated with simultaneous exposure to multiple
carcinogenic chemicals. Cancer risks for a single carcinogen are calculated by multiplying the
3 - 20
carcinogenic chronic daily intake (CDI)34 of the chemical by its carcinogenic slope factor as
follows:
Risk = CDI CSF
Where:
Risk = a unitless probability (e.g., 1 106
) of an individual developing
cancer over a 70-year lifetime
CDI = chronic daily intake averaged over 70 years (mg/kg-day)
CSF = carcinogenic slope factor, expressed in (mg/kg-day)1
.
A 1 106
cancer risk represents a one-in-one-million additional probability that an
individual may develop cancer over a 70-year lifetime as a result of the exposure conditions
evaluated. This linear equation is valid only at risk levels less than approximately 1 102
.
Where risks associated with chemical exposures are greater than this level, USEPA (1989)
recommends using the following equation:
Risk = 1 exp(-CDI CSF)
where:
Risk = a unitless probability of an individual developing cancer over a 70-year
lifetime
Exp = the exponential
CDI = chronic daily intake averaged over 70 years (mg/kg-day)
CSF = carcinogenic slope factor, expressed in (mg/kg-day)1
.
Because cancer risks are assumed to be additive, risks associated with simultaneous
exposure to more than one carcinogen in a given medium are aggregated to determine a total
cancer risk for each exposure pathway (USEPA 1989). Where multiple exposure pathways exist,
total cancer risks for each pathway are then summed for reasonable combinations of exposure
pathways to determine the total cancer risk for the population of concern. Refer to Appendices
D, H, and I for additional exposure pathway equations.
Approach for Calculating Noncancer Risks
In contrast with carcinogenic effects, potential noncancer effects are not expressed as a
probability. Instead, these effects are expressed as the ratio of the estimated exposure over a
specified time period to the RfD derived for a similar exposure period (e.g., CDI: chronic RfD).
This ratio is termed a hazard quotient and is calculated as follows:
HQ = CDI/RfD
Where:
HQ = hazard quotient
CDI = chronic daily intake
RfD = reference dose.
3 - 21
The estimated exposure and the reference toxicity factor are expressed in the same units
and represent the same exposure period (i.e., chronic, subchronic, or shorter-term). Where
available, toxicity factors for the noncarcinogenic effects of carcinogenic chemicals must also be
included. If the chemical-specific CDI exceeds the RfD (i.e., the HQ is greater than 1),
noncancer adverse health effects may be a concern. Exposures resulting in a HQ that is less than
or equal to 1 are very unlikely to result in noncancer adverse health effects.
Hazard quotients for individual chemicals are summed for each exposure pathway to
determine a noncancer hazard index as follows:
HI = CDI1/RfD1 + CDI2/RfD2 + . . . + CDIi/RfDi
Where:
HI = hazard index
CDIi = chronic daily intake for the ith
toxicant
RfDi = reference dose for the ith
toxicant
Where multiple exposure pathways exist, HIs for each exposure pathway are then
summed for reasonable combinations of exposure pathways to determine a total hazard index.
Typically, where a HI exceeds 1, an additional analysis is considered in accordance with
USEPA guidance (USEPA 1989). Specifically, the target organ of the effect used as the basis
for the reference toxicity factor (i.e., the critical effect) is reviewed. Where this review indicates
the potential for the primary contributors to the calculated total HIs to operate via different target
organs or mechanisms of toxicity, this potential is noted and the calculated HIs may be modified
to reflect values associated with specific target organs or effects. The uncertainty factor
associated with each toxicity factor is also reviewed to determine the validity of summing HQs.
Approach for Lead
For lead, the blood lead concentration estimates predicted by chemical-specific models
are compared with benchmark values as described in Appendix F. USEPA’s most recent
methods for evaluating lead exposures should also be considered. To assess the potential health
risks associated with lead exposures, the predicted blood lead concentrations derived using lead-
specific models are compared with blood lead benchmark values. For assessing childhood lead
exposures, USEPA uses a pharmacokinetic model to predict blood lead concentrations associated
with specified lead doses (USEPA, 1994b). The benchmark value is that the predicted 95th
percentile blood lead concentration for children be less than 10 micrograms per deciliter (µg/dL),
the minimum blood lead concentration in young children at which the Center for Disease Control
(CDC) recommend some type of follow-up (CDC, 1991). Use of this goal is interpreted as
meaning that there is a 95-percent probability that an exposed child would have a blood lead
concentration less than the target concentration of 10 µg/dL (USEPA, 1994b). For assessing
adult lead exposures, USEPA has selected protection of fetuses born to women exposed under
the conditions assumed in the model as the target population for protection (USEPA, 1996g).
Based on this determination, the benchmark value for blood lead in the fetus is also 10 µg/dL.
Approach for Radionuclides
[Reserved]
3 - 22
3.4.1.4 Uncertainty Analysis
A description of the minimum requirements for the uncertainty analysis is provided for
the Uniform Standard (see Subsection 3.3.4). For the site-specific standard, the uncertainties
need to be much more explicitly analyzed. Risk managers, decision makers, and the public need
to be aware of the uncertainties in the analysis in order to avoid becoming overly dependent upon
quantitative representations of results and to assure that nonquantifiable values are also
considered properly.
This section provides a brief overview of the goals of uncertainty, components of
uncertainty analyses, some proposed methods to determine uncertainties, and recommended
sources that more fully discuss uncertainty analysis. Uncertainty commonly surrounds the
likelihood, magnitude, distribution, and implications of risks. As a critical dimension in the
characterization of risk, uncertainties must be considered in terms of magnitude, sources, and
character. There are three sources of uncertainty in risk assessments:
Inherent randomness (Stochasticity). This type of uncertainty can be
estimated but not reduced because it is a characteristic of the system being
assessed.
Imperfect or Incomplete Knowledge of Things That Could be Known
(Ignorance). This is the “easiest” type of uncertainty to reduce or eliminate as
it becomes less as the general knowledge bases about contaminant expand.
Error (Mistakes in execution of assessment activities). This type of
uncertainty can only be estimated.
Some additional reasons why uncertainties are desirable to have identified and addressed:
Uncertain information from different sources of different quality must be
combined for the assessment.
Decisions need to be made about whether or how to expend resources to
acquire additional information.
Biases may result in so-called “best estimates” that in actuality are not very
accurate.
Important factors and potential sources of disagreement in a problem can be
identified.
Addressing uncertainties increases the likelihood that the results of an
assessment will be used in an appropriate manner.
Table 3-1 illustrates common types of uncertainty that surround exposure assessments. A
table such as this should be used to summarize the main sources of risk.
3 - 23
Table 3-1: Three Types of Uncertainty and Associated Sources and Examples for
Exposure Assessment
Type of Uncertainty Sources Examples
Scenario Uncertainty Descriptive errors Incorrect or insufficient information
Aggregation errors Spatial or temporal approximations
Judgment errors Selection of an incorrect model
Incomplete analysis Overlooking an important pathway
Parameter Uncertainty Measurement errors Imprecise or biased measurements
Sampling errors Small or unrepresentative samples
Variability In time, space or activities
Surrogate data Structurally – related chemicals
Model Uncertainty Modeling errors Excluding relevant variables
Source: United States Environmental Protection Agency (USEPA). 1996d. Exposure
Factors Handbook. Volume I-General Factors.
Part of the uncertainty analysis is to address the limitations of uncertainty analysis in risk
assessments. These include, but are not limited to:
Truly unexpected risks
Unknown frequencies of risk to real events
Cognitive biases that affect judgments about uncertainty, as well as risk
The pressures caused by social, cultural, and institutional forces upon analysis and
interpretation of uncertainty, and risk in general
Additional information on uncertainty analysis may found in the Exposure Factors
Handbook. Volume I - General Factors, 1996d, USEPA, EPA/600/8-89/043; available on
http://www.epa.gov/docs/ordntrnt/ORD/WebPubs/exposure/index.html
3.4.2 Implementing Site-Specific Risk-Based Standards
For individual known or suspected carcinogens, the remediation standard must be set to
represent an excess upper-bound lifetime cancer risk of between one in ten thousand (1x10-4
) to
one in one million (1x10-6
). Public notification is required if calculated residual cancer risks
exceed the one in one million level (1x10-6
) for residential land use or the one in one hundred
thousand (1x10-5
) level for industrial land use.
For individual systemic toxicants, remedial standards shall represent levels to which the
human population could be exposed without appreciable risk of deleterious effect. For
individual systemic toxicants, remedial standards shall represent levels where the hazard quotient
shall not exceed 1.0 (two significant digits of accuracy) (§60-3-9.4.b of the Rule).
3 - 24
Where multiple systemic toxicants affect the same target organ or act by the same method
of toxicity, the hazard index (sum of the hazard quotients) shall not exceed 1.0. Where multiple
systemic toxicants do not affect the same organ the hazard index shall not exceed 10.0 (§60-3-
9.4.b of the Rule). If the Hazard Index exceeds 1.0, further evaluations may be necessary as
discussed in Section 3.4.1.3, Approach for Calculating Noncancer Risks.
3.4.2.1 Site-Specific Risk-Based Standards for Groundwater
Site-Specific Risk-Based remedial standards for groundwater shall be established using at
least the following considerations:
Potential receptors based on the current and reasonably anticipated future use
of groundwater (§60-3-9.4.e.1 of the Rule).
The potential for groundwater to serve as a drinking water source (§60-3-
9.4.e.2 of the Rule), based on:
The total dissolved solids content greater than 2500 milligrams per liter
(mg/L)
-or-
It can be demonstrated to the director that the aquifer is not being used
and cannot be used for drinking water, and
The aquifer is not hydrologically connected to an aquifer being used for
drinking water;
The site-specific sources of contaminants (§60-3-9.4.e.3 of the Rule);
Natural environmental conditions affecting the fate and transport of
contaminants (e.g., natural attenuation) (§60-3-9.4.e.4 of the Rule);
Institutional and engineering controls (§60-3-9.4.e.5 of the Rule).
3.4.2.2 Site-Specific Risk-Based Standards for Surface Water and Sediments
Remediation standards for surface water and sediments should be established using at
least the following considerations:
Potential receptors based on the current and reasonably anticipated future use
of the site
The site-specific sources of contaminants
Natural environmental conditions affecting the fate and transport of
contaminants (e.g., natural attenuation)
3 - 25
Institutional and engineering controls
Site-Specific Risk-Based Standards for surface water and sediments are likely to be based
on recreational exposures.
3.4.2.3 Site-Specific Risk-Based Standards for Soil
Remedial standards for soil shall be established using at least the following
considerations ((§ 60-3-9.4.f of the Rule).:
Potential receptors based on the current and reasonably anticipated future use
of the site
The site-specific sources of contaminants
Natural environmental conditions affecting the fate and transport of
contaminants (e.g., natural attenuation)
Institutional and engineering controls
3.5 References
Federal Register. 1996. Proposed Guidelines for Carcinogen Risk Assessment .
61(79):17960-18011, April 23.
United States Centers for Disease Control (CDC). 1991. Preventing Lead
Poisoning in Young Children. United States Department of Health and Human
Services. October.
United States Environmental Protection Agency (USEPA). 1986. Superfund
Public Health Evaluation Manual. Office of Emergency and Remedial Response.
EPA 540/1-86/060.
United States Environmental Protection Agency (USEPA). 1989. Risk
Assessment Guidance for Superfund: Volume I- Human Health Evaluation
Manual (Part A). Office of Emergency and Remedial Response. EPA/540/1-
89/002.
United States Environmental Protection Agency (USEPA). 1990. Interim
Methods for Development of Inhalation Reference Doses. EPA/600/8-88/066F.
United States Environmental Protection Agency (USEPA). 1991a. Risk
Assessment Guidance for Superfund: Volume I- Human Health Evaluation
Manual (Part B, Development of Risk-based Preliminary Remediation Goals)
Interim. Office of Emergency and Remedial Response. Publication 92585.7-
01B. December.
3 - 26
United States Environmental Protection Agency (USEPA). 1991b. Standard
Default Exposure Factors for Superfund. Office of Emergency and Remedial
Response. OSWER Directive 9285.6-03.
United States Environmental Protection Agency (USEPA). 1992a. Risk
Assessment Guidance for Superfund. Volume I: Human Health Evaluation
Manual (Part A) - Supplemental Guidance: Calculating the Concentration Term.
Office of Emergency and Remedial Response (Washington, DC). OSWER
Directive 9285.6-03; Publication 9285.7-081; NTIS PB92-963373. May.
United States Environmental Protection Agency (USEPA). 1992b. Guidance for
Datas Usability in Risk Assessment (Part A) Final. Office of Emergency and
Remedial Response. Publication 9285.7-09A. April.
United States Environmental Protection Agency (USEPA). 1992c. Dermal
Exposure Assessment: Principles and Applications. Office of Research and
Development, Washington, DC. EPA/600/8-91/011B.
United States Environmental Protection Agency (USEPA). 1994a. Methods for
Derivation of Inhalation Reference Concentrations and Application of Inhalation
Dosimetry. EPA/600/8-90/066F. October.
United States Environmental Protection Agency (USEPA). 1994b. Guidance
Manual for the Integrated Exposure Uptake Biokinetic Model for Lead in
Children. Office of Emergency and Remedial Response. Pub. No. 9285.7-15-1,
EPA/540/R-93/081. February.
United States Environmental Protection Agency (USEPA). 1995. The Use of the
Benchmark Dose Approach in Health Risk Assessment. Office of Research and
Development. EPA/630/R-94/007. February.
United States Environmental Protection Agency (USEPA). 1996a. Superfund
Guidance for Evaluating the Attainment of Cleanup Standards. Volume I: Soils
and Solid Material. Center for Environmental Statistics.
http://www.epa.gov/ces/sfvol1/contents.htm
United States Environmental Protection Agency (USEPA). 1996b. Soil Screening
Guidance: Technical Background Document. Office of Solid Waste and
Emergency Response. EPA/540/R-95/128. May.
United States Environmental Protection Agency (USEPA). 1996c. Soil
Screening Guidance: User’s Guide. Office of Solid Waste and Emergency
Response. EPA/540/R-96/018. Publication 9355.4-23. July.
United States Environmental Protection Agency (USEPA). 1997a. Exposure
Factors Handbook. Volume I - General Factors. EPA/600/P-95/002Ba.
United States Environmental Protection Agency (USEPA). 1997b. Exposure
Factors Handbook. Volume II - Food Ingestion Factors. EPA/600/P-95/002Bb.
3 - 27
United States Environmental Protection Agency (USEPA). 1996f. Exposure
Factors Handbook (Draft). Volume III-Activity Factors. EPA/600/P-95/002Bc.
United States Environmental Protection Agency (USEPA). 1996g.
Recommendations of the Technical Review Workgroup for Lead for an Interim
Approach to Assessing Risks Associated with Adult Exposures to Lead in Soil.
December.
4 - 1
4.0 ECOLOGICAL RISK-BASED STANDARDS
Under §60-3-9 of the Rule, remediation standards must adequately protect human health
as well as the environment. The mechanism set forth to ensure compliance with the latter is the
ecological assessment protocol (§60-3-9.1.b). This subsection outlines the procedures and
requirements for preparing and conducting an ecological assessment. The procedures and
requirements are not meant to be inclusive or comprehensive. Applicants undertaking an
ecological assessment are directed to consult the references listed in Table 4-1 for general
guidance and background information. However, it should be noted that requirements and
stipulations outlined in this guidance and the Rule must take precedence in order to ensure
compliance with the voluntary remediation program.
Table 4-1: Recommended Guidance Sources for the Execution of Ecological Risk
Assessments
United States Environmental Protection Agency (USEPA). 1992. Framework for Ecological Risk
Assessment. EPA/630/R-92/001. February
USEPA. 1997. Ecological Risk Assessment Guidance for Superfund: Process for designing and
Conducting Ecological Risk Assessments. Interim Final. June 5.
USEPA . 1998. Guidelines for Ecological Risk Assessments 63 CFR 26846-26922 (1998)
USEPA; Region 3. 1991. EPA Region III Guidance on Handling Chemical Concentration Data
Near the Detection Limit in Risk Assessments. Interim Final. November 4.
USEPA; Region 3. 1994. Use of Monte Carlo Simulations in Risk Assessment. EPA/903/F-
94/001. February.
An ecological assessment, much like its counterpart in human health risk assessment, has
separate components of increasing detail and specificity. However, unlike the procedures for
human health risk assessment all applicants are expected to perform a De Minimis Ecological
Screening Evaluation. If the results of the De Minimis analysis indicate the presence of potential
receptors of concern and complete pathways of exposure, then the applicant may elect to either
undertake a Uniform Ecological Evaluation or proceed directly to the development of Site-
Specific Ecological Risk-Based Standards. The conceptual site model (CSM) developed in
Subsection 2.2.4 of this guidance provides the basis for the design of the ecological risk
evaluation/assessment.
The three types of evaluation that constitute the ecological assessment protocols are
developed in greater detail below:
De Minimis Ecological Screening Evaluation—This is the first step in the
ecological assessment process (§60-3-9.1.b.1). The De Minimis Screen is
intended to determine whether ecological receptors of concern are exposed to
site-related stressors. The De Minimis Ecological Screening Evaluation
differs from the human health De Minimis Standard in that no quantitative
standards are involved other than a comparison to water quality standards for
4 - 2
aquatic life (46 CSR 1). It is intended to simply evaluate whether any
potential pathways of exposure to site contaminants exist. If exposure
pathways exist and ecological receptors of concern are present, the criteria
outlined in §60-3-9.5.a of the Rule should be used to further evaluate whether
assessment is needed under the Uniform or Site-Specific Standards (See
Figure 4-1). All applicants are expected to perform a De Minimis Ecological
Screening Evaluation.
Uniform Ecological Evaluation—If the De Minimis Ecological Screening
Evaluation indicates that further assessment of ecological risk is needed, an
applicant may elect to proceed to a Uniform Ecological Evaluation (§60-3-
9.1.b.2). In this analysis, contaminant concentrations in soil and sediments are
compared to generic benchmarks, approved by WVDEP, that reflect no
significant ecological risk to specific receptors of concern. Contaminant
concentrations in surface water are compared to surface water quality
standards for the protection of aquatic life. If no surface water quality
standard for the protection of aquatic life exists for a particular contaminant,
the procedure outlined in 46 CSR 1, section 9 (CSR, 1996) may be used to
develop benchmark values as comparison criteria. As in the human health
Uniform Standard, if the benchmark values for media other than surface water
are less than natural or anthropogenic background, the background
concentrations are used as the comparison criteria. If a contaminant’s
concentration exceeds the comparison criterion, then the applicant may choose
to remediate the environmental media using the criterion concentration as a
remediation standard or develop a site-specific ecological risk-based value.
Ecological Site-Specific Risk-Based Standards—If a valid exposure pathway
exists and ecological receptors of concern (See Rule Sec. 2.14) are present,
the applicant may choose to develop site-specific risk-based standards. This
may be performed as a baseline ecological risk assessment where the specific
attributes and parameters of the site and the receptor(s) of concern are used to
determine their ecological risk from the contaminants. If the risk associated
with the contaminant(s) exceeds the acceptable risk (as per 60.8.1.e), it may
be necessary to remediate the site using site-specific values as remediation
standards. As in the human health Site-Specific Standard, if the calculated
values are less than natural or anthropogenic background, the background
concentrations are used as the remediation standards. In addition, surface
water quality standards for aquatic life must be met.
Local conditions may be considered to decide whether a site is degrading an aquatic
habitat (§60-3-9.5.a.3). In cases where a site does not present an ecological risk over and above
“local conditions” and further release of contaminants into the aquatic environment has been
stopped, there will be no need for further evaluation beyond completion of the De Minimis
checklist (Appendix C-2).
If no complete exposure pathway exists and the site does not meet any of the other
criteria outlined above, then no further ecological analysis or remediation, based on ecological
risk, is required (§60-3-9.5.c). If, however, the site meets any of the listed criteria in §60-3-9.5.a
4 - 3
and exposure pathways can be demonstrated to exist between the site contamination and any
ecological receptors of concern, then the applicant may elect to undertake an Uniform Ecological
Evaluation or proceed directly to the development of Site-Specific Ecological Standards. A flow
chart illustrating this decision process is provided in Figure 4-2.
4 - 4
FIGURE 4-1
DEMINIMIS ECOLOGICAL SCREENING
EVALUATION (REVISED)
Refine conceptual
site model
(see Figure 2.1)
Proceed directly to remedy
evaluation unless there is a
reason to conduct further
ecological risk evaluations
Completed
exposure pathway
60-3-9.5.a.1
Readily
apparent harm to
biota or habitat
60-3-9.5.a.5
Site size,lack of estimated
risk to ecological receptors,lack of valued ecological
receptors warrantscreening out60-3-9.5.a.2
Ecological
risk over and above
local conditions*
60-3-9.5.a.3
Are valued
ecological
resources present
60-3-9.5.a.4
Initiate Uniform Ecological
Evaluation or Site-specific
Ecological Risk Assessment
Yes
Prepare Final Report
on Deminimis
Ecological Risk
Screening
No
Yes
No
No
Yes
No
No
Yes
Yes
* An answer of "no" to this question
is conditioned on further release of
contaminants into the aquatic
environment having been stopped
H:\22759\003\0000\worddocs\Fig-4-1.vsd
4 - 5
FIGURE 4-2: ECOLOGICAL RISK ASSESSMENT
Either Uniform Ecological
Evaluation (Benchmark Screening)
or Site-Specific Ecological Assessment Required
(see Figure 4-1)
Further Evaluate Using
Uniform Ecological Evaluation
(Benchmark Screening)
Concentrations
of COCs
< Uniform
Benchmark
Included in
Final Report With
Human Health Standards
Clean-up to Either Human Health Standard
or Ecological Benchmark
Whichever is Lower (1)(2)
Further Evaluate Using
Ecological Site-Specific
Risk Based Standard
Concentrations
of COCs
< Site-Specific Standard
Clean-up to Either Ecological Standard
or Human Health Standard
Whichever is Lower (1)(2)
(1) Prior to clean-up the applicant must evaluate the remedial alternatives, submit a
Remedial Action Plan, and obtain WVDEP approval of the plan.
(2) Assumes background has been determined (see Subsection 2.5)
No
Yes
No
Yes
4 - 6
4.1 De Minimis Ecological Screening Evaluation
A De Minimis Ecological Screening Evaluation includes an assessment of the physical
and ecological characteristics of the site and the nature and extent of contamination to determine
if there are complete exposure pathways to ecological receptors of concern. If there are no
complete exposure pathways between contaminants of concern in environmental media and
ecological receptors of concern, it can be concluded that contaminants at the site pose no
significant ecological risk (§60-3-9.1.b.1 of the Rule). Decisions associated with the De Minimis
Ecological Screening Evaluation are illustrated in Figure 4-1.
At the screening stage of the ecological assessment process, the goal is to confirm the
presence of a contaminant release, an ecological receptor of concern, and an exposure pathway.
Actual site concentrations will not be a consideration, at this screening stage unless a valid
exposure pathway can be demonstrated. Site contamination can be identified concurrently with
the requirements for site characterization and the human health risk assessments.1
Receptor and
pathway identification specific to the ecological evaluation must be performed to fulfill the
mandated screening requirements. A checklist is provided in Appendix C-2 to aid in completion
of the screening.
If the site does not pass the De Minimis Ecological Screening Evaluation then additional
ecological risk evaluations are necessary at that site (see Sections 4.2, 4.3, and 4.4 of this
Guidance Manual). Failure to pass the De Minimis Ecological Screening Evaluation is not
equivalent to a finding that there is an ecological risk at a particular site; such a failure is only a
finding that additional evaluation is required.
This section of the Guidance Manual focuses on the use of the “Checklist to Determine
the Applicable Ecological Standard” provided in Appendix C-2. The checklist process and logic
are illustrated in Figure 4-1. This checklist is based on Section 60-3-9.5.a of the Rule. The
checklist is divided into five sections, each corresponding to one or more sections of the Rule, as
follows:
- Step 1. Determine whether a De Minimis Ecological Screening Evaluation is
appropriate for your site (see 60-3-9.5.a.1)
- Step 2. Identify any readily apparent harm or exceedances of Water Quality
Standards (see 60-3-9.5.a.5)
- Step 3. Identification of contamination associated with ecological habitats (see
60-3-9.5.a.2 and 60-3-9.5.a.3)
- Step 4. Characterize the potential ecological habitat (see 60-3-9.5.a.4)
1 It is important to note that although contaminant analysis for ecological assessments may be conducted concurrently with the human health
assessment, special considerations must be taken into account. For example, ecological benchmarks are sometimes lower than the corresponding
human health-based standards. Therefore, it would be prudent to ensure that the sample detection limit for a given contaminant is appropriate.
Furthermore, the distribution of the contamination should be evaluated not only with regard to human exposures, but also exposures to potential ecological receptors of concern.
4 - 7
- Step 5. Identify any potential ecological receptors of concern (see 60-3-9.5.a.4
and the definition of “ecological receptors of concern” at Section 2.14 of the
Rule)
This section of the guidance addresses Steps 1, 2, and 3 in the following three subsections. Step 4
and 5 are addressed together in a fourth succeeding subsection. The last subsection discusses the
reporting requirements for this screening process and checklist. Examples outlining the
application of this screening process and the checklist are provided at the end of this section.
4.1.1 Determination of a Potential Complete Exposure Pathway
An exposure pathway is a direct or indirect physical association between a contaminant
originating from the site and an ecological receptor of concern. An exposure pathway should be
considered complete if an ecological receptor of concern is reasonably expected to contact a
contaminant from the site via exposure to any environmental medium, including biota.
Therefore, the presence of a complete exposure pathway will require a source and mechanism of
contaminant release to the environment, an environmental transport medium, a point of potential
contact between an ecological receptor of concern and the environmental medium, and a feasible
exposure route at the contact point. Assumptions regarding contaminant transport or fate should
be conservative and prudent to ensure that all relevant exposure pathways are evaluated.
Contaminated media for consideration in the De Minimis Ecological Screening
Evaluation includes soil, sediments, surface water and biota. Groundwater may also be an
important medium of exposure through uptake of shallow groundwater by deep-rooted plants and
in the transport of contaminants into a surface water body. Table 4-2 outlines the type of
exposure routes that must be considered in identifying potential complete exposure pathways.
Table 4-2: Expected Routes of Exposure Based on the Medium of Contamination
Media Direct Receptor Exposure Indirect Media Exposure
Soil Dermal contact Leaching to groundwater
Ingestion Runoff to surface water and sediments
Gas/particulate inhalation Food chain contamination
Plant uptake
Sediments Direct contact Transport to surface water
Ingestion Bulk transport downstream
Plant uptake Food chain contamination
Surface Water Direct contact Bulk Transport downstream
Ingestion Saturation and capillary transport to soil
Ventilation Absorption in sediments
Plant uptake Food chain contamination
Groundwater Plant Uptake (shallow
groundwater
Discharge to surface water
Biota Ingestion
.
4 - 8
If there has not been a release to the environment at or from the site, the De Minimis
Ecological Screening Evaluation can be concluded based on the lack of contaminated media,
and, therefore, an exposure point. If no habitat exists that could be affected by site-related
contamination, the De Minimis Ecological Screening Evaluation can also be concluded based on
the lack of any potential ecological receptors of concern (§60-3-9.5.a.1).
To fulfill the requirements of the ecological De Minimis Ecological Screening
Evaluation, a demonstration must be made for the presence or lack of pathways of exposure
between the contamination and the ecological receptor(s) of concern. A Certificate of
Completion will only be granted if none of the following conditions are found to apply:
A contaminant stressor has migrated off-site and has become widely
distributed in the environment (§60-3-9.5.b.1).
Wildlife or ecological resources (receptors) of concern are exposed or have
the potential for exposure to stressors (contaminants), either on or off-site
(§60-3-9.5.b.2).
Remediation of contamination at the site has the potential to expose ecological
receptors of concern to adverse impacts (§60-3-9.5.b.3).
There is a potential for indirect or cumulative impacts to ecosystems of
concern (§60-3-9.5.b.4).
Rare or sensitive species of concern are potentially at risk (§60-3-9.5.b.5).
Adverse ecological effects have been observed in otherwise high quality
habitats (§60-3-9.5.b.6).
Projected land use involves the presence of sensitive ecosystems (§60-3-
9.5.b.7). See Section 2.2.3.2.
4.1.2 Identifying Readily Apparent Harm
Sites which have been the cause of readily apparent ecological harm, or sites where there
is a significant risk of harm to biota or habitats do not pass the De Minimis Ecological Screening
Evaluation. If any one of the following criteria are observed at the site, then readily apparent
harm is found:
Visual evidence of stressed biota attributable to the release at the site,
including, but not limited to, fish kills or abiotic conditions
Visible presence of oil, tar, or other non-aqueaous phase contaminant in soil
over an area greater than two acres, or over an area equal to or greater than
1,000 square feet in sediment.
A risk of ecological harm would exist if it were reasonable to forecast any of these
conditions as occurring in the future due to site-related constituents of concern.
4 - 9
For sites with readily apparent harm or the risk of such harm, both the Rule and practical
experience suggest that further ecological evaluation may be redundant and unproductive. It may
be more appropriate for the respondent to postpone further ecological evaluations until some
remediation has been implemented and the readily apparent harm has been controlled or, at least,
mitigated. In cases of readily apparent ecological harm, the purposes of VRRA would be best
served, in most cases, by prompt remedial action to control the source and to address the
impacted media to the maximum and quickest extent. As a minimum, the respondent should
proceed promptly to remedy selection and implementation.
4.1.3 Identifying Contamination Associated with Ecological Habitats
Although a release to the environment may have occurred or natural habitat is located on
or near the site, the De Minimis Ecological Screening Evaluation can be concluded at this stage
if the following two conditions are met:
Environmental media associated with the onsite and adjacent habitat have been
sampled and analyzed, and the site-related contaminants have not been detected
above background concentrations
Site-related constituents are not currently migrating to aquatic habitats, including
wetlands
If both of these conditions are not met, or if site contamination has not been
investigated, the respondent must proceed with identification of potential ecological
habitats and receptors of concern
4.1.4 Identifying Potential Ecological Habitats and Receptors of Concern
Ecological receptors of concern are defined as specific ecological communities,
populations, or individual organisms protected by federal, state, or local laws and regulations or
those local populations which provide important natural or economic resources, functions, and
values.
As discussed in Subsection 4.1.1, if no habitat exists that could be affected by
contamination related to the site, the De Minimis screening can be concluded based on the lack
of any potential receptors of concern (§60-3-9.5.a.1). If, however, natural habitats exist, progress
toward identifying receptors of concern should begin with a description of each habitat.
Descriptions of all potential habitats should address the following:
General type of habitat
Location of the habitat relative to the rest of the (site considering potential
transport pathways)
Area and topography of the defined habitats
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Predominant physical and geographical features
Dominant plant and animal species known to occur at the site
Soil and sediment types
Human encroachment and interactions, including historical disturbances
Evidence of Natural disturbance
Once it has been established that natural habitats exist and they have been described and
characterized, it is necessary to identify potential assessment endpoints. The criteria for
selecting assessment endpoints, upon which receptor selection will depend, are based on the
management goals developed for the site. The Management goals for the De Minimis Ecological
Screening Evaluation should address the protection of ecological receptors of concern.
The presence of ecological receptors of concern will depend on the habitat on and near
the site. Those receptors residing or otherwise utilizing the valued environments listed in
Subsection 2.2.3.2 shall be identified as ecological receptors of concern. If such habitat is
identified within or near the site, a complete exposure pathway may exist and it will be necessary
proceed with further ecological risk assessment. The applicant may elect to either undertake a
Uniform Ecological Evaluation or proceed directly to the development of Ecological Site-
Specific Risk-Based Standards. Note that there may be additional requirements that apply under
federal law in the case of threatened or endangered species. The requirements are not preempted
by the Voluntary Remediation Program.
State and regional wildlife agencies, local governments, interest groups, and universities
are available to provide technical assistance in the identification of potential receptors. The West
Virginia Division of Natural Resources2 and the regional offices of the U.S. Fish and Wildlife
Service3 maintain wildlife databases including information on threatened and endangered
species. Other sources that may be helpful in these determinations are listed in Table 4-3. An
onsite investigation should follow the initial habitat analysis. The purpose of the onsite
investigation is to verify that the previously identified habitat can support potential ecological
receptors of concern and to ensure that other potential receptors were not overlooked. The
results of this investigation should be documented for inclusion in the work plan. The final
selection of receptors, along with criteria and rationale, must be included in the final report as
part of the listing of technical standards pursuant to §60-3-6.1.g of the Rule.
2 Wildlife Database Manager, WV Division of Natural Resources, P.O. Box 67, Elkins, WV 26241, phone (304) 637-0245. 3 U.S. Fish and Wildlife Service, P.O. Box 1278, Elkins, WV 26241, phone (304) 636-6586.
4 - 11
Table 4-3: Reference Sources for Species Distribution Information
WV-DNR Natural Heritage Database (Rare, Threatened, and Endangered Species)
http://www.heritage.tnc.org/nhp/us/wv
WV-DNR (Game Species)
Bucklew, A. R., Jr., and G. A. Hall. 1994. The West Virginia Breeding Bird Atlas.
University of Pittsburgh Press. Pittsburgh, PA. 215 p.
Hall, G. 1983. West Virginia Birds: Distribution and Ecology. Carnegie Museum of
Natural History. Pittsburgh, PA. 180 p.
Green, N. B., and T. K. Pauley. 1987. Reptiles and Amphibians in West Virginia.
University of Pittsburgh Press. Pittsburgh, PA. 241 p.
Stauffer, J. R. Jr., J. M. Boltz and L. R. White. 1995. The Fishes of West Virginia.
Academy of Natural Sciences of Philadelphia. Philadelphia, PA. 389 p.
Allen, T. 1997. The Butterflies of West Virginia and Their Caterpillars. University of
Pittsburgh Press. Pittsburgh, PA. 388 p.
Mussels of West Virginia (In Preparation, contact Janet Clayton, WV-DNR)
Strausbaugh, P. D., and E. L. Core. 1973. Flora of West Virginia. Seneca Books, Inc.
Grantsville, WV. 1079 p.
WVU Herbarium (County-by-County Database in Preparation)
4.1.5 Reporting Requirements
A report on the execution of the De Minimis Ecological Screening Evaluation must be
included in the final report in accordance with §60-3-11.3 of the Rule. If the assessment is
completed prior to the submission of the work plan, it should be included in support of proposed
future assessments and remediation activities (§60-3-10.5.b). The report should be structured to
address the questions presented in the checklist provided in Appendix C-2 for determining the
applicable standard. It should also include any validated sampling data, a description of the
habitat characterization and identification of any assessment endpoints, measurement endpoints
and receptors of concern. The report should also describe the presence or absence of exposure
pathways.
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4.2 Uniform Ecological Evaluation
A Uniform Ecological Evaluation (as described in §60-3-9.1.b.2 of the Rule) is a generic
evaluation of the potential effect a site’s contamination may have on identified ecological
receptors of concern. It is a screening analysis that compares the site-specific concentration of a
contaminant with WVDEP-approved standards or criteria in order to determine whether it
represents a potential threat to ecological communities associated with the site.
4.2.1 Benchmarks and Generic Exposure Models for Uniform Ecological Evaluation
The Uniform Ecological Evaluation involves comparing the concentrations of stressors in
environmental media with generic standards or benchmarks. These standards are intended to
protect the most sensitive ecological receptor(s) of concern as defined in the management goals.
Selection of suitable reference concentrations is discussed below.
Sources of appropriate ecological benchmarks, as outlined in §60-3-9.6 of the Rule, are
listed in Table 4-4. The receptors of concern used in this analysis should be those identified in
the De Minimis Ecological Screening Evaluation. Methods for determining anthropogenic
background levels are outlined in Subsection 2.5 and Appendix B of this guidance. Derivation
of applicant derived benchmarks are outlined in Subsection 4.2.4.
Table 4-4: Approved Sources and Methods for the Derivation of Medium-Specific
Ecological BenchmarksA
Media Benchmark/Toxicity Data Sources
Surface Soilb and Sediment Anthropogenic Background Levels
Direct Contact Benchmarksc
Applicant Derived Values for Direct Contactd
Surface Water Federal Ambient Water Quality Criteria
State Water Quality Criteria
Anthropogenic Background Levels
Applicant Derived Valuesd
Groundwatere Federal Ambient Water Quality Criteria
State Water Quality Criteria
Anthropogenic Background Levels
Applicant Derived Valuesc
a Sources are listed in §60-3-9.6 of the Rule. b Surface soil constitutes the layer no greater than 2 ft below the surface. c This category is limited to benchmark values available from sources outlined in Table 4-4 and Appendix G. d This method is only to be used if no state or federal criteria exist. See Subsection 4.3.4 of this guidance. e Groundwater should only be considered if it is expected to affect a surface water body of concern (§60-3-9.6.c).
4.2.2 Applicant-Derived Benchmarks for Uniform Ecological Evaluation
If no criterion or appropriate benchmark exists for a given stressor, it is the responsibility
of the applicant to derive an appropriate benchmark. The benchmark value must be based on
either the bounded NOAEL or LOAEL derived from peer-reviewed sources for the contaminant
4 - 13
stressor specific to the contaminated medium and the receptor of concern (60-3-9.6.b.2). This
usually referred to as the toxicity reference value (TRV). The TRV is a level of exposure that
represents the maximum at which no significant ecological risk exists. A particular TRV is
specific both to the receptor and stressor. It is empirical in that it is based on a specific dose-
response relationship derived from experimental observations. TRVs for typical ecological
receptors are available.
Approved sources for TRVs are listed in Table 4-5 and Appendix G. For receptors that
must be protected on an individual basis (e.g., special status species), the TRV is the bounded
NOAEL for the respective receptor and stressor. If the receptor is to be protected at the
population level, the TRV is the dose that is likely to induce a population-level response.
Criteria for the evaluation of an appropriate TRV are listed in Table 4-6. Benchmark values may
be developed using the formulas provided in Figures 4-3 through 4-6.
With appropriate documentation, site-specific input parameters for the equations are
preferred over default values. If there are numerous receptors of concern, then the screening
criteria should be established based on the receptor whose exposure and toxicological sensitivity
results in the lowest benchmark screening value. For surface water, the benchmark criterion is
usually the TRV (in mg/l) that is protective of all aquatic receptors. If the most sensitive
receptor exposed to surface water is terrestrial, then the model in Figure 4-3 should be used. For
other environmental media, models and inputs are provided in Figures 4-4 through 4-6.
Table 4-5: Acceptable References for the Derivation of Benchmark ValuesA
EPA AQUIRE database (www.epa.gov/earth100/records/a00120.html)
EPA IRIS Database(www.epa.gov/ngispgm3/iris/)
EPA HEAST Database
EPA ASTER Database (www.epa.gov/earth100/records/a00122.html)
EPA PHYTOTOX Databaseb
EPA Terrestrial Toxicity Database (TERRATOX)b
USFWS Technical Reports
Oak Ridge National Laboratory Toxicological Benchmark Technical Reports
(www.hsrd.ornl.gov/ecorisk/reports.html)
Other EPA documents acceptable to DEP
ATSDR Toxicological Profiles (www.atsdr.cdc.gov/toxpro2.html)
Other peer-reviewed publicationsc
Data developed in accordance with a peer-reviewed scientific testing protocol and approved by DEP
a These references are listed as acceptable under §60-3-8.1.c.2 of the Rule. No priority should be inferred
from the order they are presented. bAccess available through ECOTOX (www.epa.gov/superfund/oerr/r19/ecotox)
cAdditional references for benchmark values are provided in Appendix G.
4 - 14
Table 4-6: Criteria For The Evaluation Of TRVs
Does the nature of the response have a direct impact on the measurement endpoint?
Is the response the most sensitive effect to be expected?
Is the mode of exposure consistent with the conceptual model?
Is the TRV specific to the stressor as it occurs in the medium on-site?
Is the expected response associated with the TRV consistent with the routes of
exposure?
Is the TRV relevant to the receptor and its habitat conditions on-site?
Were appropriate allowances made for interspecies comparisons?
- Application of uncertainty factors
- Use of secondary interspecies application models
- Comparable considerations of bioavailability relative to the exposure model
4.2.3 Risk Characterization based on the Uniform Ecological Evaluation
Risk characterization in the Uniform Ecological Evaluation involves comparing the
contaminant concentrations (either the 95% upper confidence limit on the mean [UCL] or the
maximum value) to the appropriate benchmark values specific to the receptors of concern. If a
contaminant’s concentration in an environmental medium is less than the benchmark, it may be
assumed that it represents no significant ecological risk and no further action need be considered.
If the contaminant’s concentration in the medium exceeds the benchmark, there is a potential for
unacceptable risk. While field survey data are valuable for understanding current environmental
conditions, they are not used under the Uniform Standard to determine adverse effects to
ecological receptors of concern. The use of field survey data is appropriate under the Site-
Specific Standard.
When more than one chemical is present, the potential for additive, synergistic or
antagonistic effects should be discussed. This discussion will usually be qualitative, except for
cases where quantitative estimates of relative toxicity are available, e.g., dioxins, PCBs, or
organophosphates. Interactions among chemicals are considered most likely when chemicals are
known to affect the same toxic endpoint, e.g., reproductive effects. If multiple chemicals are
present which have the same toxicity endpoint and toxicity data are available, the concentrations
should be summed and compared to a single benchmark that has been approved by the WVDEP.
If a substantial number of chemicals with similar toxic endpoints are present and toxicity data are
not available, the potential for interactions should be discussed even if no benchmarks are
exceeded.
4 - 15
If field survey data show readily apparent harm where several chemicals are involved,
benchmarks selected should consider interactive or synergistic effects.
If a stressor exceeds a benchmark concentration, then there are two alternatives available
to the applicant: 1) the benchmark is accepted as the remediation standard for that stressor, or 2)
the applicant may undertake a site-specific ecological evaluation to determine a remediation
standard unique to the particular site.
Figure 4-3A: Equations for the Derivation of Benchmarks for Surface Water Specific to
Terrestrial Receptors
IR
TRVSWSTL
Where:
SWSTL = Mean surface water screening threshold limit (mg/l)
TRV = Toxicity reference value (mg/kg bw day)
IR = Intake rate (l/kg bw day)
4 - 16
Figure 4-3: Equations for the Derivation of Benchmarks for Soil
Where the TRV is derived from water exposures which assumed 100%
bioavailability, the following equations are to be used:
Where the TRV is derived from soil exposures
IRTRVSSTL /
Organic Contaminants:
SSTL
TRV k fH
n
IR
oc oc
w a
s
'
( )1
Inorganic Contaminants:
SSTLTRV
IR
pH pKa
107
Where1:
SSTL = Mean soil screening threshold limit (mg/kg soil dw)
TRV2 = Toxicity reference value (mg/kg bw day)
koc3 = Water-organic carbon partition coefficient (l/kg soil dw)
foc = Fraction of organic carbon (kg/kg; default0.01656)
w = Water filled pore space (l/l; default 0.3)
a = Air filled pore space (l/l; default 0.13)
H’ = Henry’s law constant (unitless)
n = Soil porosity (l/l; default 0.43)
s = Particle density (kg/l; default 2.65)
pH4 = Soil pH (default 4.7
6)
pKa = Log equilibrium constant for hydroxide formation
IR = Intake rate (kg dw/kg bw day)
Intake Rates:
For plants: IR = 1
For passerines: IRW
W
0 398 0 85. .
For herbivorous mammals: IRW
W
0577 0 727. .
For predatory mammals: IRW BAF
W
0 235 0 822. .
For predatory birds: IRW BAF
W
0 648 0 651. .
Where:
W = body mass (g)
BAF = Biomagnification Factor5
4 - 17
Figure 4-3: Equations for the Derivation of Benchmarks for Soil Cont’d
Notes:
1 Unless otherwise stated, all default values were taken from the USEPA’s Soil
Screening Guidance (1994)
2 The TRV used should be the lowest for all terrestrial receptors of concern
associated with the site.
3 The koc may be estimated from the contaminant’s octanol-water partition
coefficient (kow) using the following equation:
Log k x Log koc ow( ) . . ( ) 2 8 10 0 9834
4 Median values for 181 West Virginia Soils (Jenks. 1969)
5 BMFs are chemical and receptor-specific parameters.
Figure 4-4: Equations for the Derivation of Benchmarks for Sediment
Organic Contaminant:
SdSTL ATV f koc oc
Inorganic Contaminant:
SdSTL ATV pH pKa 107 Where
1:
SdSTL = Mean sediment screening threshold limit (mg/kg sediment dw)
ATV2 = Aquatic Toxicity Value (mg/l)
koc3 = Water-organic carbon partition coefficient (l/kg)
foc = Fraction of organic carbon (default 0.20)
pH = Sediment pH (default ?)
pKa = Log equilibrium constant for hydroxide formation
1 Unless otherwise stated, all default values were taken from the USEPA’s
Sediment Quality Criteria (1993)
2 If available, use the appropriate ecological ambient water quality criteria.
Otherwise, use the lowest TRV (in mg/l) for all aquatic receptors of concern
associated with the site.
3 Refer to figure 4-3, note 3 for the derivation of the Koc from the contaminant’s
Kow.
4 - 18
Figure 4-5: Equations for the Derivation of Benchmarks for Groundwater
GwSTLDr
TrATV
Where:
GwSTL = Mean groundwater screening threshold limit (mg/L)
Dr = Groundwater discharge rate (L/day)
Tr1
= Surface water turnover rate (L/day)
ATV2 = Aquatic Toxicity Value (mg/L)
1 If the surface water body is a creek or river, then substitute the mean flow
volume (l/day) for the turnover rate.
2 If available, use the appropriate ecological ambient water quality criteria.
Otherwise, use the lowest TRV for all aquatic receptors of concern associated
with the site.
4.2.4 Reporting Requirements for the Uniform Ecological Evaluation
The results of the Uniform Ecological Evaluation are to be included in the final report in
accordance with §60-3-11.3 of the Rule. If the assessment is completed prior to the submission
of the work plan, it should be included in support of proposed assessment and remediation
activities (§60-3-10.b). The report should identify ecological receptors of concern and media
contamination upon which exposure pathways are based. It should also list appropriate
benchmarks and discuss their sources and derivations. Comparisons of contaminant
concentrations to their benchmarks should be presented in tabular form for each medium. The
report on the Uniform Ecological Evaluation should also include a clear discussion of the
screening results and an analysis of the uncertainty associated with any of the quantified values.
4.3 Ecological Site-Specific Risk-Based Standards
The development of ecological risk-based site-specific standards is analogous to
developing a baseline ecological risk assessment. Applicants may choose to develop
remediation standards through this process instead of relying on the benchmark standards
derived in the Uniform Ecological Evaluation. The process for ecological risk assessment
generally follows the guidance’s listed in Table 4-1 and involves problem formulation, exposure
analysis, ecological effects, and risk characterization. These steps are described in the
subsequent sections.
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4.3.1 Problem Formulation
The problem formulation component addresses the management goals through the
definition of the assessment and measurement endpoints, identification of the receptor(s) of
concern, and the development of the CSM and the analysis plan. The process for defining the
endpoints and receptors is discussed in Subsection 4.1.1 under the De Minimis Ecological
Screening Evaluation. The following is an example of the development of management goals
and assessment and measurement endpoints.
Management goal: Maintenance of fish communities
Assessment endpoint: Maintenance of a benthic community that can serve as a
prey base for local fish populations
Measurement endpoints:
concentrations of chemicals of concern in
sediment and water column relative to levels
reported in scientific literature to be harmful
toxicity observed in a whole sediment bioassay
at levels considered significant according to test
protocol; and
benthic invertebrate community structure /
productivity relative to reference areas
Measurement endpoints should be weighted, giving the most weight to the measurement
endpoint that best represents the assessment endpoint, allowing it to have the greater influence
on the conclusions of the risk assessment. Attributes to be considered which help to define how
well a measurement endpoint represents the assessment endpoint include: 1) strength of
association between assessment and measurement endpoints, 2) data quality, and 3) study
design and execution. This process is described in Menzie et. al., 1996.
4.3.1.1 Quantifying Measurement Endpoints
In the De Minimis and Uniform Evaluations, measurement endpoints were considered
qualitatively to identify the ecological receptors of potential concern. In the development of site-
specific standards, it will be necessary to establish quantitative limits on the measurement
endpoints to characterize the relationship between the contaminants of concern and the receptor
population effects. The methods employed will be specific to the particular situation being
considered. A review of the scientific literature and guidance documents listed in Table 4-1 will
provide examples that may be applicable.
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4.3.1.2 Refinement of the Conceptual Site Model (CSM)
The CSM is a series of working hypotheses regarding how the contaminant(s) interact
with the ecological receptor(s) of concern. Refinement of the CSM will help in quantifying the
measurement endpoints. Examples of criteria that the conceptual site model should address
include the following:
Is the model sufficiently quantitative to associate the stressor to the
measurement endpoint via the receptor?
Does the model directly reflect the habitat of consideration?
Does the model account for all media and all potential routes of exposure?
Does the model adequately reflect the concerns inherent in the management
goals?
Based on the results of the CSM, an analysis plan should be formulated. The analysis
plan is the practical description of the methods and strategies that will be used to meet data
requirements of the conceptual model(s). It should include the types of media and biota to be
sampled, the contaminants to be analyzed for as well as the potential ecological habitats and their
characterization requirements. The analysis plan will ensure that there is adequate site-specific
information to perform the risk analysis as well as providing a useful tool in the identification of
data gaps for the subsequent uncertainty analysis.
Although the establishment of the measurement endpoints, the CSM, and the analysis
plan should be done early in the assessment process, they must be considered amendable and
open to modifications during the course of the site investigations as new information develops.
Flexibility is essential in problem formulation to ensure completion of a precise and cost-
effective site-specific ecological assessment.
Further discussion of the development of a conceptual site model is provided in
Subsection 2.2.4 of this guidance document.
4.3.2 Quantitative Exposure Analysis
The quantification of receptor exposure to a stressor requires the numerical description of
both the nature of the contaminant and the impact it has on the receptor as it interacts with that
environment. The former is defined by contaminant fate and transport models (See Subsection
2.4.13) and the latter by the risk characterization.
In selecting pathways for evaluation, the applicant may take into account the availability
of toxicity information in the scientific literature. There is a paucity or complete absence of
scientific information on several pathways (e.g., inhalation and dermal contact for a large
number of contaminants and a majority of potential receptors of concern (see Table 4-2). Such
pathways need not be evaluated if the applicant can document a lack of quantitative information
in the scientific literature, however, a qualitative assessment should be discussed in the risk
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characterization and uncertainty subsections (see 4.3.4 and 4.3.6). Field surveys maybe used to
help determine whether COPCs are having an adverse effect on receptors. However, the
WVDEP will continue to monitor this area and, if appropriate information becomes available,
the applicant will be advised.
Sometimes both exposure and effects are assessed directly using media toxicity testing or
biological field surveys. The application of these direct toxicity analyses is most commonly used
for assessments of lower and middle trophic organisms. For higher trophic receptors, it is
usually neither practical nor economical to determine the actual toxicity. Therefore, it becomes
necessary to model the potential impact based on the exposure the receptor is likely to incur and
the toxicity threshold above which an adverse effect may be sustained. Considerations for this
type of assessment are discussed below.
4.3.2.1 Biological Field Surveys
Field surveys are a method used to determine whether evidence of an adverse impact can
be identified and correlated with contaminant concentrations within the environment. The scope
of the survey is based on the measurement endpoints established in the problem formulation
phase. The performance of a biological field survey involves the cataloging of wildlife present
within the habitat under evaluation. Within this context, the field survey should be performed
with sufficient detail and statistical precision to permit a quantitative comparison with a
reference site that is similar to the site under investigation in all respects possible with the
exception of the contaminant(s) under investigation. The detail required should be sufficient not
only to determine if there has been any adverse impact, but also to reasonably attribute such
impacts to the appropriate cause.
4.3.2.2 Direct Toxicity Determinations
The determination of potential risk may also be made through the application of direct
toxicity testing. This is most common in the assessment of surface waters and sediments,
although it may be applied to other environmental media. In direct toxicity testing, an
indigenous or sentinel species is exposed to samples of the site media, usually under laboratory
conditions, and the toxicity of the medium is determined based upon its effect on a measurement
endpoint (e.g. lethality, reproduction, malformations, etc.). Examples of this type of direct
toxicity analysis would include the Daphnia survival/reproduction assay for surface water or the
10-day Hyalella or Chironomus toxicity test for benthic macroinvertebrates in sediment
(SETAC. 1993). Care must be taken to ensure that the results of direct toxicity testing are
applicable to the overall risk characterization of the site. This is best accomplished by
comparing the results to a reference site that is similar to the site under investigation in all
respects possible with the exception of the contaminant(s) of potential concern.
4.3.2.3 Receptor Exposure Models
Receptor exposure models are mathematical constructs used to estimate the amount of a
contaminant to which a specific receptor or population of receptors is likely to be exposed. The
two major considerations in receptor exposure models are direct contact with contaminated
4 - 22
media and indirect contact through contaminated foodstuffs. Parameters used as variables in the
fate, transport and exposure models should ideally be derived from site-specific observations.
Where this is not practical, default assumptions, approved by WVDEP, may be used.
Direct Exposure to Contaminated Media—A receptor of concern will be
exposed to a contaminant if it is found in direct contact with a contaminated
medium. The receptor exposure model determines the actual dose of the
stressor that the receptor is expected to receive. For animals, direct exposure
usually occurs through a combination of dermal contact, respiration, and
ingestion4. For plants, exposure occurs through deposition, stomatal infusion
and/or evapotranspirative uptake. The specific exposure is the product of the
amount of environmental medium contacted, the contaminant’s concentration
in the environment and the proportion of the contaminant that is likely to be
absorbed by the receptor. Attenuation factors may also be used if the affected
habitat only accounts for a portion of the receptor’s total range, or if
absorption of the chemical stressor is expected to be less than complete. When
evaluating absorbance efficiencies, it is important to consider this parameter
relative to the bases of the comparative TRV and not just that of the absolute
absorbance. The total direct exposure to a stressor is the sum of all specific
exposures by all pathways. Model equations for the determination of direct
exposure are listed in Figures 4-6, 4-7 and 4-8.
Figure 4-6: Model Equations for Direct Ingestion Exposure
Soil and Sediments:
D C IR Bais s s s [ ] 10 6
Water1:
D C IR Baiw w w w [ ]
Where:
Dis = Exposure dose from ingestion of soil or sediment (mg/kg day)
Diw = Exposure dose from ingestion of water (mg/kg day)
[Cs] = Concentration of contaminant in soil/sediment (mg/kg)
[Cw] = Concentration of contaminant in water (mg/l)
IRs = Soil/sediment ingestion rate (mg/kg day)
IRw = Water ingestion rate (l/kg day)
Bas = Proportional Bioavailability from soil/sediment
Baw = Proportional Bioavailability from water
1 This model is to be applied to terrestrial receptors only. For aquatic receptors, water
ingestion is considered a component of direct contact.
4 Exposure to a contaminant through drinking water will be considered a direct exposure for the purpose of
this analysis.
4 - 23
Figure 4-7: Calculation Model for the Exposure of Receptors Through the Ingestion of
Biota
D C Ba IRf k k k
k
m
[ ] 10001
Where:
Df = Average daily dose (mg/kg day)
m = Number of contaminated food types
[Ck] = Average contaminant concentration in food k (mg/kg)
Bak = Proportion absorbed from foodstuff k
IRk = Daily intake rate of item k (g/kg day)
In some situations, it may not be possible to directly determine the concentration of a
contaminant within a receptor’s food item(s). In these cases, it will be necessary to estimate the
concentration based on the foodstuff/prey’s exposure and a Biomagnification factor. The model
for this type of estimate is provided in Figure 4-10. Biomagnification factors are empirical
estimates that possess a high degree of uncertainty particularly when applied in situations
different than those in which they were derived or over multiple trophic levels.
Biomagnification factors tend to be very conservative and should only be considered when site-
specific data cannot be obtained. Sources for bioaccumlation factors, biomagnification factors
and food chain multipliers are limited but available from various USEPA guidance’s as well as
the scientific literature.
Figure 4-8: Models for the Estimation of Biota Contamination Based on Medium
Contamination Concentration
[ ] [ ]C C BMFk m
Where:
[Ck] = Contaminant concentration in foodstuff/prey item (mg/kg)
[Cm] = Contaminant concentration in environmental media (mg/kg)
BMF = Biomagnification factor
Determination of BMF:
BMF BAF FCM
Where:
BAF = Bioaccumulation factor: BAFC
C
T
m
[ ]
[ ]
1
[CT1] = Contaminant concentration in first trophic level
FCM = Food chain multiplier (contaminant-specific)
4 - 24
Total Exposure Profiles—The total exposure is the sum of total direct and total indirect
exposure. It is the value (or distribution) that will be used in the risk characterization analysis.
Estimates of total exposure are to be reported in terms of central tendency (mean or median) as
well as plausible upper-bound estimates (e.g., 95th percentile) pursuant to § 60-3-8.7.h of the
Rule.
4.3.3 Ecological Response Analysis
The ecological response analysis is the phase where comparative toxicity values are
generated in order to evaluate the risk from exposure. Its primary function is to provide a
standard against which the contamination exposure under investigation may be measured. The
standard should represent a level of exposure that is considered allowable or acceptable.
Evaluation on the suitability of the standard is based on the values inherent in the management
goals and should be detailed within the analysis plan.
If the risk analysis is to be based upon either a biological field survey or direct toxicity
analyses, then an acceptable habitat standard must be established to which the results are to be
compared (pursuant to 60-8.1.3.2). In most cases, the results are compared to a reference area
that represents an ecologically acceptable condition and is similar in all respects possible with
the exception of the contaminant(s) of potential concern. Alternately, the site may be compared
to a hypothetical construct of what would be expected under acceptable circumstances, although
this method tends to be highly uncertain.
If the risk characterization is to be based on exposure modeling, then the effects analysis
must provide a threshold dosage that the specific receptor of concern may be exposed to without
incurring an unacceptable risk for an adverse effect. This is usually referred to as the TRV.
Approved sources for TRVs are listed in Table 4-4. For receptors that must be protected on an
individual basis (e.g., special status species), the TRV is the bounded NOAEL for the respective
receptor and stressor. If the receptor is to be protected as the population level, the TRV is the
dose that is likely to induce a population-level response. Criteria for the evaluation of the
applicability of a TRV are listed in Table 4-6.
If probabilistic methodologies are to be employed in the response analysis, then the
estimations developed as part of a probabilistic method must fall within the bounds of the dose-
response curve. Determinations based on unbounded estimates of toxicity should be avoided.
4.3.4 Risk Characterization
Risk characterization is the phase of the risk assessment where a value is placed on the
potential impact that a stressor has on the ecological environment. This value is an expression of
the risk based on the evaluation of the measurement endpoints. In most cases, the risk is
expressed in a Boolean fashion; that being whether an acceptable risk exists or not. The
definition of acceptability is evaluated on the assessment endpoints based on the parameters
established in the management goals. If the risk characterization demonstrates that conditions
for a site exceed the bounds of acceptable risk, then, under the Rule (§ 60-3-9.7.b), remediation
may be necessary prior to the granting of a status of no further action required. Decisions on the
4 - 25
appropriate remediation measures required in order for the site to conform to the management
goals should be determined on a weight-of-evidence basis. If an adverse effect can be
demonstrated to have occurred and that effect can be attributed to the contaminant, then it may
be necessary to consider remediation at the site.
4.3.4.1 Risk Characterization Based on Biological Field Surveys
When characterizing risk based on biological field surveys, the biological condition of
the site is compared to the reference established in the ecological effects analysis. This
comparison must meet two specific considerations in order for a risk to be attributed to a specific
contaminant. The first is whether any differences observed between the site under investigation
and the reference represents an adverse impact. This may require a level of professional
judgment since no two habitats are ever identical. The determination of an adverse effect is best
based on quantifiable differences in the character of the habitats such as significant differences in
biodiversity or productivity. The second consideration is whether any detectable adverse effect
can be directly attributable to the contaminant in question. This must be determined through a
process of elimination where all other potential factors that could affect the habitat are ruled out
until a characteristic adverse effect can be reasonably attributed to the presence of the
contaminant.
4.3.4.2 Risk Characterization Based on Direct Toxicity Testing
Risk characterization based on direct toxicity testing is similar to that of characterization
by the biological field survey in that it is based on comparison to a reference situation either real
or hypothetical, that is within the definition of acceptable as defined by the management goals.
Here, the effects analysis defines a rate of toxic response that is the threshold for acceptable risk.
If the medium toxicity from the site under investigation statistically exceeds that level, then the
risk of an adverse effect is deemed unacceptable. Similarly as with the biological field survey
method, it is necessary to ascribe the causative stressor through a process of elimination.
However, unlike field surveys, it is much easier to ascribe a threshold concentration based on the
results of the toxicity tests and concurrent medium contamination analysis. This can then be
used as a site-specific benchmark to evaluate other portions of the site that have not been directly
tested for toxicity.
4.3.4.3 Risk Characterization Based on Exposure Models
Risk characterization using exposure models entails comparing the site-specific exposure
results against the TRV derived in the effects analysis to determine whether there is a significant
ecological risk. This comparison is to be made regardless of whether single-point or
probabilistic methods are employed. For point-estimate analyses, this is accomplished by
calculating a hazard quotient for each stressor and receptor. The format for the calculation of
single point estimates is detailed in Figure 4-9. For probabilistic determinations, the receptor
response threshold (or distribution) is compared to the approximated response corresponding to
the 90th
percentile of the exposure distribution (§60-3-9.7.c).
4 - 26
Figure 4-9 Model Calculations for the Determination of Hazard Indices
HID D D D D D
TRVn
ds dw is iw f o n
n
( )
Where:
HIn = Hazard index for contaminant n
Dds=Exposure resulting from direct contact with soil/sediment(mg/kg day)
Ddw = Exposure resulting from direct exposure to water (mg/kg day)
Dis = Exposure resulting from ingestion of soil/sediment (mg/kg day)
Diw = Exposure resulting from ingestion of water (mg/kg day)
Df = Exposure resulting from ingestion of foodstuffs (mg/kg day)
Do = Exposure resulting from any other significant route (mg/kg day)
TRVn = Toxicity reference value for contaminant n (mg/kg day)
If the ratio of the exposure concentration to the TRV (or the approximate receptor
response to the threshold response) is less than 1 for receptor, it can be concluded that no
significant ecological risk exists for that receptor. If, however, the hazard quotient is greater than
1, then an unacceptable risk is deemed to exist under the Rule (§60-3-9.7.b), and remediation
may be necessary.
4.3.5 Remediation Standards Based on Ecological Risk
If it is found that a particular receptor/stressor interaction represents a significant
ecological risk, then it will be necessary to establish site-specific, risk-based standards. This is
accomplished by calculating a concentration for the stressor in an environmental medium that
corresponds to an exposure level for the receptors of concern that does not exceed the lowest
TRV. For surface water, the remediation benchmark is equivalent to the TRV for the identified
receptors of concern with the highest HI. This value may be compared to a daily average
concentration for the entire water body and should not necessarily be applied as a “not-to-
exceed” value.
4.3.6 Uncertainty Analysis
The uncertainty analysis identifies the uncertainty associated with the various steps of the
risk assessment process. This information is vital for interpreting the results of the risk
assessment in the remedial decision making process. Descriptions of uncertainty should be as
complete and detailed, as possible and should cover both quantitative and qualitative aspects of
the assessment process. A partial list of potential sources of uncertainty that may be included in
this analysis is provided in Table 4-7. Table 4-8 identifies specific considerations to be included
in the uncertainty analysis for the ecological risk assessment final report. Additional guidance
on uncertainty analysis may be found in USEPA guidances listed in Table 4-1.
4 - 27
If probabilistic methodologies were employed in the risk assessment, the uncertainty
associated with the selection of the data distribution, compensation for potential correlations, and
the bounded limits of the inputs should be addressed in the uncertainty analysis. Furthermore,
the results of all sensitivity analyses should be included and discussed with regard to the
uncertainty inferred from the distribution of the results. Further information on the reporting of
uncertainly associated with probabilistic models may be found in Appendix H of this guidance.
4.3.7 Reporting Requirements
At the completion of the site-specific risk assessment, the applicant should be able to
communicate to WVDEP a reasonable estimate of ecological risks, indicate the overall degree of
confidence in the risk estimates, cite lines of evidence supporting the risk estimates, and interpret
the ecological adversity. This information is to be outlined in the final report as required under
§60-3-11.2 of the Rule. It is important that the risk assessment results be presented in a manner
that is clear, transparent, reasonable, and consistent to facilitate its use in making risk
management decisions. Specific aspects particular to the ecological risk assessment process are
listed in Table 4-8.
4 - 28
Table 4-7: Potential Sources of Uncertainty
Source Considerations
Habitat
Characterization
Theoretical or empirical basis for the inclusion or exclusion of regions as
habitats
Identification of species present in identified habitats
Evaluation of the significance of the habitat to potential receptors
Characterization of physical attributes of habitat
Characterization of ecological attributes of habitat
Stressor Distribution Selection of stressors of concern
Sensitivity and errors associated with media sampling
Data gaps in sampling (spatial, temporal, media types)
Identification of pathways for stressor transport
Assumption and uncertainty in statistical models of stressor distribution
Endpoint and
Receptor Selection Presence or absence of threatened or endangered species
Basis for the selection of measurement endpoints
Significance of the measurement endpoint to the quality of habitat
Causal association of the receptor to the endpoint
Ecological significance of receptor(s)
All quantifications of the ecological models employed
Exposure Models Applicability of selected models to site-specific conditions
(including fate and
transport modeling) Quantification limits of selected exposure models
Basis for the selection of default assumptions in the quantitative models
Error associated with site-specific parameters and input variables
Response Models Basis and applicability of response models to specific receptors of concern
Basis for the selection of default assumptions in the quantitative models
Applicability of quantified toxicity values and other input variables
Extrapolation of toxicological response to population and measurement
endpoints
Confidence in the accuracy of the dose-response relationship
4 - 29
Table 4-8: Critical Items to be Included in the Final Report on site-specific Ecological Risk
Assessment
Results and basis for the problem formulation
Description of and rationale for the management goals, assessment and
measurement endpoints, and receptor selection
Presentation of the conceptual model and the assessment endpoints.
Discussion of the major data sources and analytical procedures used.
Review of the exposure and response analyses.
Description of the risks to receptors, including quantitative risk estimates.
Review and summary of major areas of uncertainty and the approaches used to
address the uncertainty.
Discussion of generally accepted scientific positions on issues of inherent
uncertainty (e.g., inter-species extrapolation of toxicity information).
Identification of major data gaps and, where appropriate, indication of
whether gathering additional data would significantly reduce uncertainty.
Discussion of science policy judgments or default assumptions used to
bridge information gaps, and the basis for these assumptions.
4.4 References
Jenks, E. M. 1969. Some chemical characteristics of the major soil series of
West Virginia. West Virginia University Agricultural Experiment Station
Bulletin 582T. Morgantown, WV.
Menzie, M., Henning, M.H., Cura, J., Finkelstein, K., Gentile, J., Maughan, J.,
Mitchell, D., Petron, S., Potocki, B., Svirsky, S., and Tyler, P. 1996. Special
Report of the Massachusetts Weight-of Evidence Approach for Evaluating
Ecological Risks. Human and Ecological Risk Assessment. Vol. 2, No. 2., pp.
277-304.
Society of Environmental Toxicology and Chemistry (SETAC). 1993. Guidance
Document on Sediment Toxicity Tests and Bioassays for Freshwater and Marine
Environments. Editors: Hill, I.R., Matthiessen, P. and Heimbach, F. November.
4 - 30
Suter, G.W., Barnthouse, L.W., Bartell, S.M., Mill, T., Mackay, D., and Paterson,
S. 1993. Ecological Risk Assessment. Lewis Publishers.
United States Environmental Protection Agency (USEPA). 1989. Ecological
Assessment of Hazardous Waste Sites: A Field and Laboratory Reference.
USEPA, Environmental Research Laboratory, Corvallis, OR. EPA/600/3-89/013.
United States Environmental Protection Agency (USEPA). 1993. Technical
basis for Establishing Sediment Quality Criteria for Non-Ionic Organic
Contaminants for the Protection of Benthic Organisms by Using Equilibrium
Partitioning. EPA-822-R-93-011. Office of Water. Washington, DC. September
USEPA. 1993. Wildlife Exposure Factors Handbook. EPA/600/R-93/187a
(Volume I) and EPA/600/R-93/187b (Volume II).
USEPA. 1994. Methods for Measuring the Toxicity and Bioaccumulation of
Sediment-Associated Contaminants with Freshwater Invertebrates. EPA/600/R-
94/024. June 1994.
USEPA. 1996a. Soil Screening Guidance: Technical Background Document.
EPA/540/R-95/128. Office of Solid Waste and Emergency Response.
Washington, DC. May.
5 - 1
5.0 RESIDUAL RISK ASSESSMENT
As stated in §8.6 of the Rule, a residual risk assessment (RRA) may be conducted
considering conditions that will be present at the site following implementation of a proposed
remedy. The RRA should consider and evaluate both human health and ecological risk.
Included in the RRA is an assessment of the risks under current and reasonably anticipated future
land and water use scenarios under the following conditions.
The exposure conditions that will be present following remediation and the
concentrations of untreated waste constituents or treatment residuals
remaining at the conclusion of any excavation, treatment, or off-site disposal
(§8.6.b.l); and/or
The exposure conditions that will result following implementation of any
institutional or engineering controls necessary to manage risks from treatment
residuals or untreated hazardous constituents (§8.6.b.2).
The RRA must follow the same basic procedures outlined in Sections 3 and 4 of this
guidance document, except that the conditions used to define the site must reflect post-
remediation conditions, including site-specific numeric remediation standards and site-specific
exposure conditions that incorporate any engineering and institutional controls proposed as part
of the remedial action. It is not necessary to develop a RRA at sites where any one of the three
risk-based standard indicates no further action is the proposed remedy.
At some sites, the RRA may be the only risk assessment performed to obtain a certificate
of completion. Examples may include, but are not limited to:
Sites where the applicant has already implemented a remedial action (e.g., a
removal action has taken place and the risk assessment can now be performed
using concentrations of contaminants remaining after the removal action) or
Sites where harm is readily apparent (described in Section 4, ecological
standards) and the applicant has elected not to perform a risk assessment but
proceed directly to the remedy evaluation.
6 - 1
6.0 PROBABILISTIC RISK ASSESSMENT
Probabilistic risk assessments may be completed for the site-specific standard for both
human health and ecological risk assessment. Probabilistic methods may be applied to describe
parameter values required in transport and fate modeling, environmental media concentration
data, exposure parameters, and toxicity estimates for both human and ecological populations.
Combining probabilistic descriptions of some or all of these parameters will yield a probabilistic
risk characterization. Techniques to perform probabilistic risk assessments are provided in
Appendix I.
Probabilistic techniques are not necessary for all risk assessments, therefore, a tiered
approach is recommended. In all cases, both human and ecological risk assessment, a
deterministic calculation should be done first. If the results of this calculation show that either 1)
site risks are so low so as to warrant no remediation, or 2) site risks are so high that there is no
question but that remediation must be performed, then a probabilistic risk assessment is most
likely unnecessary. However, if the deterministic risk assessment shows that site risks are in the
range where the decision whether to remediate or not falls, then a probabilistic risk assessment
can be of use to better define the range of likely risks and their uncertainty. In these instances, a
probabilistic risk assessment can assist in making risk management decisions.
7 - 1
7.0 REMEDY SELECTION AND EVALUATION
7.1 General
It is anticipated that sites entered into the VRRA program will vary greatly in terms of
size, nature and extent of contamination, human health and ecological risks, physical conditions,
and other pertinent factors. The process of remedy selection and evaluation must, therefore, be
flexible to facilitate appropriate responses to the full range of sites and management issues. As
long as the selected remedy or remedies satisfy the evaluation criteria established in §60-3-9.8 of
the Legislative Rules, there is no intent to restrict the range and remedies considered or the
process of remedy selection. In some cases, it may not be necessary to consider a variety of
candidate remedies so long as the selected remedy meets the criteria of §60-9.8a of the rule.
The approaches to remedy identification and selection provided in this section are offered
as guidance only. There is no regulatory mandate to apply the methods outlined in this section.
The guidance related to remedy identification and selection is organized in two parts, as
follows:
Remedy identification with a bibliography of information sources on various
types or categories
Remedy evaluation discussing the criteria established in the Legislative Rule
with a bibliography of information sources on remedy evaluation.
Natural attenuation is discussed, in terms of the specific regulatory criteria for approval
of this approach, in subsection 7.5 of this guidance (Section 7.5).
The Voluntary Remediation Agreement (VRA) and the Workplan must demonstrate that
the selected remedy or combination of remedies have been evaluated in relation to the criteria
established in the Legislative Rule. If the site is divided into multiple units for the purpose of
remediation, the remedy for each unit must be evaluated in relation to these criteria. The VRA
and Workplan are not required to describe the selection process or the remedies considered and
the reasons for their selection or nonselection. However, discussions of the remedy selection
process, the candidate remedies considered, and the evaluation of each candidate remedy may be
appropriate components of the VRA or Workplan to assist in demonstrating that the selected
remedy or combination of remedies is appropriate for that particular site.
The guidance provided in this section is not intended to restrict the range of candidate
remedies considered and/or selected for any particular site as long as the selected remedy meets
the evaluation criteria. Specifically, there is no intent to restrict or discourage use of innovate
methods. Similarly, there is no intent to recommend or give preference to any particular remedy,
category of remedies or to any product, service or vendor.
7 - 2
7.2 Identification of Candidate Remedies
The first step in remedy selection and evaluation is the identification of candidate
remedies based on the analysis of the nature and extent of contamination and the cleanup
objectives.
Table 7-1 provides a partial list of candidate remedies by environmental media.
Although these lists are not complete, they do indicate the wide range of remedies available for
each media. Table 7-1 should be viewed with the following notes or comments in mind:
Many of the table entries represent categories of remedies, with different
treatment reagents, microbes, process units, or methods available to address
various site conditions, contaminants, and contaminant concentrations.
Some candidate remedies will have beneficial impact on more than one
environmental media. For example, the pumping and treating of groundwater
may reduce soil contamination levels if contaminants can migrate to the
saturated zone. Similarly, in situ chemical or biological treatments may
address both soil and groundwater contamination.
Many of the treatment processes identified in Table 7-1 are marketed and
supported by process, reagent, and/or equipment vendors. Typically, each
process is supported by multiple vendors. Further, specialized consultants and
laboratories offer services related to process evaluation, reagent or microbe
selection, and treatment formula development.
There are a variety of data sources available to assist in remedy selection and
evaluation. These sources include government publications (federal and state
agencies), reference books by commercial publishers and associations, buyer’s
guides in industry magazines, and internet-accessible electronic data bases.
Subsection 7-6 presents a partial bibliography of published and electronic data sources to
assist in remedy identification and evaluation.
7.3 Initial Screening of Candidate Remedies
An initial screening should be conducted to select a short list of appropriate alternatives
for evaluation from the universe of remediation technologies. Based on the available
information, only those technologies that apply to the media or source of contamination should
pass the initial screening and be evaluated. The use of presumptive remedy guidance, where
available, can in many cases provide immediate focus to the selection of alternatives.
Presumptive remedies such as landfill caps (Ref EPA Presumptive Remedy Document) involve
the use of remedial technologies that have been consistently selected in the past at similar sites or
for similar contaminants.
7 - 3
Table 7-1: Partial Listing of Potential Candidate Remedies by Media
Soils Groundwater Surface Water and Leachate
No action
Natural attenuation (passive
or intrinsic remediation)
Excavation and off-site
disposal with treatment
(typically hazardous waste)
Excavation and off-site
disposal without treatment
(typically non-hazardous
waste)
On-site, ex situ thermal
treatment
On-site, ex situ chemical
treatment
On-site, ex situ
fixation/stabilization
On-site, ex situ biological
treatment
Soil vapor extraction
Passive soil venting
Soil washing
Soil flushing
Cap/cover over source area
Containment around source
area
In situ chemical treatment
In situ biological treatment
In situ fixation/stabilization
No action
Natural attenuation (passive
or intrinsic remediation)
In-well aeration
Air sparging
Dual phase vacuum
extraction and treatment
Extraction pumping and
chemical treatment
Extraction pumping and
biological treatment
Extraction pumping and
physical treatment
In situ biological treatment
In situ chemical treatment
Funnel-and-gate technology
Vertical barriers
Inceptor trenches
Rock fracturing and
enhanced groundwater
collection (with appropriate
treatment)
Cap and cover
Containment (e.g., slurry
wall, tight sheeting, etc.)
No action
Natural attenuation (passive
or intrinsic remediation)
Collection and chemical
treatment
Collection and biological
treatment
Collection and physical
treatment (e.g., filtration,
aeration)
Cut-off wall or flow barrier
upgradient of source
Surface water flow diversion
Cap/cover over source area
Containment around source
area
7 - 4
7.3.1 Screening Criteria
Candidate remedies should be screened initially against the following broad criteria:
Applicability and Appropriateness to Site
Consider the specific contaminants present and their extent; the impacted
media; the size of the site; the nature, extent, and status of the sources of
contamination; and the physical condition of the site to identify potential
remedies that appear to be applicable and appropriate to the specific site.
Give further consideration only to those candidate remedies that are
considered to be appropriate and applicable to the specific site.
Technical Feasibility
Consider the steps and procedures required to implement each potential
remedy in relation to site-specific conditions (site size, topography, current
land use, future land use – if known, drainage routes, surface conditions and
materials, subsurface conditions, and other factors) to assess the technical
feasibility, practicality, and probability of success of applying that remedy to
the specific site. Also consider the performance history (beneficial impact,
implementation problems and other relevant information) of the candidate
remedy at other sites with similar characteristics. Give further consideration
only to those candidate remedies that are evaluated as technically feasible at
the specific site.
7.3.2 Screening Method
The initial screening should be conducted in accordance with the following general
methodology:
Pass/fail evaluation of each candidate remedy against each screening criterion
subsection 7.3.1.
Further consideration only of remedies “passing” the two criteria – no further
consideration of remedies “failing” either criteria.
The initial screening should be considered as brief, focused, and informal, and
is not required to be reported.
The candidates passing both screening criteria (i.e. the short list remedies) qualify for
further evaluation.
7 - 5
7.4 Evaluation of Short-List Remedies
This section sets out seven criteria for those technologies passing the initial screening
criteria.
7.4.1 Evaluation Criteria
For those remedies passing the screening criteria, this section describes the seven criteria
used for further evaluation.
1. Effectiveness in Protecting Human Health and the Environment
Each remedy is evaluated for the ability to eliminate, reduce or control the
identified exposure pathways. Short and long term impacts and potential
cross-media impacts are identified and evaluated.
The remedy is evaluated relative to attainment of the identified remediation
standard goals.
During assessment of this evaluation criteria, additional requirements to
implement each remedy including institutional and/or engineering controls are
identified.
2. Long-Term Reliability to Achieve Standards
Evaluation of long-term reliability of each remedy includes the following:
Assessment of Residual Risks
- Magnitude
- Type (treatment residuals and/or residual contamination)
- Assessment of Reliability
- To meet cleanup goals
- Nature and extent of long-term management
- Long-term monitoring requirements
- Operation and maintenance requirements
- Identification of difficulties and uncertainties associated with implementation
- Component replacement requirements
- Duration of institutional and/or engineering controls
3. Short-Term Risks Posed by Implementation
Each remedy is evaluated to identify short-term risks during
implementation (construction phase through achievement of cleanup
goals) by consideration of the following:
7 - 6
Assessment of Risks to Workers
- Identification of risks
- Identification of risk mitigation methods
Assessment of Risks to Site Neighbors and the Community
- Identification of risks
- Identification of risk mitigation methods
Assessment of Risks to the Environment
- Identification of environmental impacts
- Identification and assessment of mitigation measures
- Identification of unavoidable impacts
Assessment of Time Required for Remediation Implementation
- Identification of time frame for construction
- Identification of time frame to achieve cleanup goals
4. Acceptability to the Affected Community
An assessment of the acceptability to the affected community involves identifying
the affected community (if any), potential issues of concern, and review of
comments received under §60-3-7.4 of the Rule (only applies to brownfield
applicants). Although there is no requirement in the rule, applicants are
encouraged to seek community input in reviewing remedial alternatives that may
potentially cause offsite impacts. If permitting is a requirement, this also needs to
be considered. As appropriate, mitigation measures are identified and evaluated.
5. Implementability and Technical Practicability
The implementability and technical practicability of each remedy are assessed by
evaluation of the following.
Assessment of Technical and Engineering Feasibility
- Technical difficulties and unknowns
- Reliability of technology
- Ease of implementation
- Monitoring requirements
Assessment of Administrative Feasibility
- Permit requirements
- Consistency with other applicable regulations
Assessment of Availability of Services, Equipment and Materials
- Availability of treatment, storage, and disposal services
- Availability of equipment
- Requirements for specialized equipment
7 - 7
- Availability of workers
- Availability of technology
6. Cost Evaluation
Consider the following elements as they are applicable to the remedy being
evaluated:
Capital costs
- Engineering costs including process development, design services, and
related support activities
- Process equipment including ancillary equipment and process control
devices
- Labor, materials, and equipment to install or construct the remedy
including earthwork, foundations, structures, and utilities (including cap,
containment, or other site work items, if appropriate)
- Contractors overheads, allowances for general tools and supplies, and
profit
- Site costs during construction such as support facilities, utilities, fencing,
and security
- Permits and other fees
- Construction management including procurement of equipment and
contracted services and construction supervision
- General administrative costs
- Health and safety items
Operating Costs
- Operating and maintenance labor
- Maintenance parts and supplies
- Treatment reagents and/or other operating supplies
- Operating utilities
- Health and safety items
- Required reporting
- Site management and administration costs during the remedy operating
period
Monitoring and reporting costs e.g.
- Sampling and analysis of results as required or appropriate
- Collection and analysis of perimeter and/or environmental monitoring
samples
- Collection and analysis of progress and/or confirmatory samples
In many cases, candidate remedies will have variations in the projected timing of
expenditures. This is most likely to be the case when remedy implementation extends
into the future for several years or more. If the differences in the amounts and timing of
these expenditures are significant, it may be appropriate to calculate the present worth of
the stream of expenditures for each candidate remedy. Under these circumstances,
present worth calculations will provide a more useful and valid economic comparison of
the remedies being evaluated.
7 - 8
Present worth calculations provide estimates of the current values of future
expenditures by considering both the time-value of money (i.e., the effective discount on
money deposited now at interest to meet future obligations) and the increases of future
costs due to inflation. Present worth calculations are done using standard methods and
formulas. Textbooks in financial analysis and engineering economics provide detailed
explanations of present worth calculations and formulas (subsection 7.6.5). Pocket
calculators programmed with the appropriate financial analysis formulas to facilitate
these calculations are available at modest cost; such calculators come with clear, step-by-
step instructions to assist the user.
Making present worth evaluations requires estimation of future interest and
inflation rates. This can be simplified by recognizing that the object of these calculations
is the comparison of alternate remedies, so consistency in using the factors is more
important than the actual factors applied. A useful approximation can often be developed
by applying a risk-free, inflation-free interest rate and a zero inflation rate to the present
worth formulas. Specific information on project interest rates and inflation rates can be
found in general business publications. Local bankers and/or librarians may be able to
assist in developing this information.
7. Net Environmental Benefits
An evaluation of the net environmental benefits of a remedy includes the
following:
Consideration of the projected reduction in quantity, toxicity, mobility, and risk.
Consideration of potential site reuse.
- Restrictions
- Time frame for reuse
7.4.2 Evaluation Method
Each candidate remedy should be evaluated against the seven criteria specified in the
Rule as described above. This evaluation may be done for a short list of candidate remedies. It
may be useful to provide a concise report of the alternatives considered and the evaluation
conducted to support the demonstration that the selected remedy meets the human health and
environmental protection criteria. The remedy meeting the effectiveness in protection criteria,
achieving remediation standards, and with the lowest overall cost (including present worth
calculation, if appropriate) should be selected unless there are extenuating circumstances
favoring the selection of another candidate remedy. The Rule leaves remedy selection to the
discretion of the remediating party as long as the selected remedy meets the protectiveness
criteria for both human health and the environment.
The remediating party is required only to identify the selected remedy and demonstrate
that it meets the protectiveness goals. There is no requirement to report the selection process or
to establish a formal remedy evaluation and selection process comparable to the Feasibility
Studies required for “Superfund” or the Corrective Measures Studies required for RCRA
Corrective Actions.
7 - 9
7.5 Inclusion of Natural Attenuation in Remedy Evaluation
Section §60-3-9.9 of the Rule allows for submission of a remediation plan which includes
the natural attenuation of contaminants of concern contained in soils, sediments, and/or
groundwater for the entire site or portions of the site. The Rule provides conditions which must
be met and/or demonstrated for the Department to approve natural attenuation as a viable
remedy. This section provides guidance for the regulated community to compile the evidenced
needed for such a strategy.
Section §60-3-9.9 of the Rule specifies several environmental criteria which must be
demonstrated before the WVDEP will approve a natural attenuation remediation plan. These
conditions include:
1. That the contaminants of concern have the capacity to degrade or attenuate
under site-specific conditions (§60-3-9.9a).
2. That the contaminant plume in groundwater or soil volume is not
increasing in size (§60-3-9.9.b).
3. That all sources of contamination and free product have been controlled or
removed, where applicable (§60-3-9.9b).
4. The contaminant migration will not result in the violation of applicable
groundwater standards (46CSR1) at any existing or reasonably foreseeable
receptor (§60-3-9.9d).
5. A groundwater discharge to a surface water body will not result in
contaminant concentrations at the sediment/water interface that result in
violations to the surface water standards (46CRS12) (§60-3-9.9f).
Natural attenuation of inorganic and organic compounds in soils, sediments, and
groundwater can occur by a number of mechanisms, primarily biological and physical. Physical
mechanisms for natural attenuation include sorption, dilution, volatilization, and dispersion.
Biological mechanisms include biodegradation, which results in the destruction of contaminants
by aerobic and anaerobic microorganisms. To support remediation by natural attenuation, it
must be scientifically demonstrated that attenuation of site contaminants is occurring at rates
sufficient to be protective of human health and the environment. Much of the information
needed for a natural attenuation strategy will be collected as part of the site characterization
phase and the investigation of the extent of contaminant migration. However, some of the
evidence needed to support natural attenuation is quite specific, and therefore, for efficiency,
collection of data to support natural attenuation as a remedial option should be considered as part
of the early phases of the investigation (see for additional guidance OSWER Directive 9200.4-
17, “Use of Monitoring Natural Attenuation at Superfund, RCRA Corrective Action, and
Underground Storage Tank Sites).
7 - 10
7.5.1 Developing Evidence in Support of Natural Attenuation
There are several steps to take in gathering the evidence needed to support natural
attenuation. These steps are directed towards pursuing three technical lines of evidence:
1. Documented mass loss of contaminants.
2. Presence and distribution of geochemical and biochemical indicators.
3. Direct microbiological evidence.
The following paragraphs outline the steps to be taken to gather the necessary evidence,
and provide guidance for completion. This guidance is primarily geared toward natural
attenuation in groundwater, however, the same principles apply to the natural attenuation of
contaminants in soils. Depending on the location an depth of the soil contamination, it may be
necessary to utilize institutional or engineering controls to: 1) prevent potential receptor
exposure to contaminated soils from the site, and/or 2) mitigate soil that acts as a contaminant
source groundwater.
7.5.1.2 Review Available Site Data for Evidence of Natural Attenuation
Historical data of contaminant concentrations can provide some of the most defensible
evidence for natural attenuation if there has been a mass loss of contaminants at the site. In
addition, the existing data may provide evidence for both geochemical and biochemical
indicators of intrinsic bioremediation (i.e., presence of daughter products, byproducts of
microbial respiration, loss of electron acceptors, etc.). This step serves to define data needs and
the locations of additional monitoring points as well as determining the likelihood of exposure
pathway completion.
7.5.1.3 Develop a Preliminary Conceptual Site Model
The conceptual site model is a presentation and explanation of the contaminant
distribution in site groundwater in relation to contaminant fate and transport processes. This
model should include:
The location of the source(s) of contamination. As stated above, the source(s)
of contamination must be controlled or removed, where practicable. If the
source(s) of contamination cannot be controlled or removed, the effect of the
continuing source(s) on contaminant fate and transport relative to the rate of
the natural attenuation processes must be considered in the conceptual model.
The relative distribution of the COCs, both vertically and horizontally, in soil
and groundwater.
The location of potential human and ecological receptors.
7 - 11
Site specific characteristics which make the site amenable to natural
attenuation.
An estimate of the contaminant transport velocity and direction of
groundwater flow. §60-3-9.9c of the Rule requires that the travel time and
direction of contaminant migration be predicted with reasonable certainty.
Estimation of the length of time necessary to achieve site specific remedial
objectives.
Further discussion of the development of a conceptual site model is discussed in Section
2.2.4 as well as in Weidemeier et al. (1995) and Feenstra et al. (1996).
7.5.1.4 Additional Data Requirements
The data required to support a natural attenuation remedial technology are specific to the
site and the type of contaminants present. Table 7-2 lists a number of soil and groundwater
parameters used to support natural attenuation; an explanation of each of these parameters is
contained in several publications (ASTM 1996; Wiedemeier et al., 1995; Wiedemeier et al.
1996a; Wiedemeier et al., 1996; RTDF Bioconsortium Guidance Handbook,
www.rtdf.org/public/biorem/default.htm. These data should be evaluated for a number of
monitoring points located:
upgradient of the source area in a non-contaminated area;
in the source area;
downgradient of the source area in the dissolved phase contaminant plume; and
downgradient of the plume.
Upgradient, or in some cases sidegradient, groundwater monitoring wells can be used to
quantify background concentrations for a number of the parameters being evaluated. For sites
having more than one aquifer or a significant vertical component of flow, monitoring well
locations should also be selected to adequately represent the vertical profile.
The analytical data collected during site characterization activities can be evaluated to
better define the biodegradation kinetics (i.e. first order decay rate). An understanding of the
biodegradation kinetics is a necessary component for quantifying input parameters used in
models that incorporate natural attenuation equations. The biodegradation kinetics are site
specific; dependent on the contaminant type, microbiological community, and available
nutrients. Contaminant type is important since various chemicals degrade at faster rates than
others. Additionally, chemicals degrade under aerobic and/or anaerobic conditions at varying
rates. A microbiological community is required for biodegradation within an environment that is
favorable for organism growth (note: pH values outside of the 6-8 range and high levels of
certain chemicals may slow community growth or be toxic to the microorganisms). The
available nutrients involve naturally occurring or engineered electron acceptors (i.e. dissolved
7 - 12
oxygen, nitrogen, sulfate, iron, carbon dioxide) and election donors (i.e., carbon sources) that are
used by the microorganisms to break down the contaminants of concern through respiration.
Methods for calculating the first order decay rates are presented in Weidemeier 1995 and
Buscheck and Alcantar, 1995). Alternatively, literature values of first order decay rates may be
obtained but must be clearly documented, justified, and qualified as subjective (Wilson et al,
1996; Howard et al 1991; Rifai, et al 1995).
Table 7-2: Parameters Used to Assess Natural Attenuation Field
Parameters
Inorganics
Organics
Dissolved
Gases
Micro-
biological
Physical
Hydro-
geological
Dissolved
oxygen
Redox
potential
Conductivity
Temperature
pH
Ammonia/TKN
Chloride
Sulfide
Sulfate
Nitrate
Nitrite
Ortho-Phosphate
Iron (total & dissolved
- field filtered)
Manganese (total and
dissolved-field
filtered)
VOCs (cis
& tans
isomers
identified)
Semi VOCs
CO2
TOC
COD/BOD
Alkalinity
(carbonate
&
bicarbonate)
Methane
Ethane
Ethene
PLFA
(Phospholipid
Fatty Acid
Analysis)
Total
heterotrophic
and
contaminant-
specific
bacterial plate
counts
Grain size
analysis
Porosity
Subsurface and
surficial geology
including
lithology,
stratigraphy, and
structure
Hydraulic
gradient
Microcosm studies are conducted only when the microbiological and chemical evidence
for natural attenuation at the site is inconclusive. Wiedemeier et al. (1995), discusses protocols
for setup and analysis of microcosm studies. Biodegradation rates obtained from microcosm
studies are often much faster than the actual field rates (Rifai et al., 1995). Therefore, results of
microcosm studies are generally used qualitatively to demonstrate that the biodegradation
processes are occurring in the field, and not to develop biodegradation rates for modeling.
7.5.1.5 Collect Additional Data in Support of Natural Attenuation
Since in situ biodegradation can proceed under both aerobic and anaerobic conditions,
sampling soils and groundwater for natural attenuation parameters must be performed in a
manner that does not change the redox potential (Eh) of these materials. In general, exposure to
oxygen and agitation of the samples must be minimized. Use of low flow purge and sample
methods with submersible or peristalitic pumps and flow-through sampling cells are
7 - 13
recommended (ASTM, 1992). Under no circumstances should bailers be used for this type of
sampling. A more complete discussion of groundwater and soil characterization for natural
attenuation can be found in Weidemeier et al. (1995: In prep.: 1996a)
7.5.1.6 Refine Conceptual Site Model
After the site data has been compiled and evaluated relative to natural attenuation
processes, the conceptual site model should be refined to more accurately reflect the fate and
transport processes affecting the contaminants of concern. This data analysis should include an
evaluation of the geological, chemical, and biological factors that affect the rate and extent of
natural attenuation. The refined conceptual site model can be used as a basis for analytical or
numerical modeling designed to simulate the migration and attenuation of contaminants. It is
mandatory that a natural attenuation strategy for a site be protective of human health and the
environment, therefore, conservative model input parameters should be used. All input
parameters should be clearly defined and justified.
7.5.2 Simulation of Natural Attenuation
Two classes of mathematical models (screening and advanced) can be used to
demonstrate that natural attenuation is a viable remedial option. Simple analytical screening
models are primarily designed to determine the feasibility of using natural attenuation as part of
a remedial strategy. At smaller sites with apparently limited impacts, it may be appropriate to
use a screening model as the primary groundwater model to simulate natural attenuation, and
predict the extent and duration of contaminant migration. One such model is BIOSCREEN,
which has been developed and endorsed by the US Air Force (Newell et al., 1996; internet
www.epa.gov/ada/csmos.html.
Sites with complex hydrogeology or multiple contaminant source areas may require the
use of an advanced numerical groundwater contaminant fate and transport model to simulate
natural attenuation and predict the extent and duration of contaminant migration. Examples of
advanced numerical models include: Bioplume II, III, RT3D, BIOMOD3-D, and BioF&T3-D.
Bioplume II is a two dimensional numerical groundwater flow model developed to
simulate oxygen limited aerobic decay. Bioplume II is most applicable to sites with relatively
simple geology (homogeneous and isotropic porous media) which are contaminated with
petroleum hydrocarbons. A new version of Bioplume II (Bioplume III) currently under
development will be able to simulate more complex microbial processes, multiple chemical
species, and aerobic/anaerobic processes (Newell et al., 1995, Rifai et al., 1987).
More advanced two and three dimensional numerical models include RT 3D
(http://terrassa.pnl.gov:2080/bioprocess/rt3d.html) BIOMOD 3-D and BioF&T 3-D (Scientific
Software Group, e-mail: [email protected]). RT3D and Biomod 3-D are typically used in
conjunction with the USGS finite-difference groundwater flow model, MODFLOW 3-D. These
models are capable of simulating groundwater flow and contaminant transport in the saturated
and unsaturated zones in heterogeneous, anisotropic porous media or fractured media. each of
these models simulate complex microbial processes based on oxygen limited, anaerobic, first-
order, or Monod type biodegradation kinetics, as well as anaerobic or first-order sequential
7 - 14
degradation involving multiple daughter species. Given the capabilities of RT3D, BIOMOD 3-D
and BioF&T 3-D, these models can be used at sites with the most complex hydrogeology (e.g.,
interbedded sands and clay, fractured bedrock, and multiple aquifers) and complex contaminant
distribution (e.g., multiple source areas and non-aqueous phase contamination), and are
applicable to most contaminants (e.g., petroleum hydrocarbons, chlorinated solvents, explosives,
and heavy metals).
7.5.3 Conduct an Exposure-Pathway Analysis
After calculating the rate of natural attenuation and predicting the future concentration
and extent of the contaminant plume, it is necessary to evaluate whether the plume has the
potential to impact receptors before contaminant concentrations have degraded to the applicable
groundwater and/or surface water standards. Both ecological and human receptors need to be
identified as well as points of exposure under current and future land, surface water, and
groundwater use scenarios. Before the agency can accept a proposal for natural attenuation, the
applicant must demonstrate that the contaminant migration will not result in the exceedance of
any groundwater standards at any existing or reasonably foreseeable human receptor, or the
exceedance of any surface water standard if the receptor is a surface water body. The standards
for surface waters are contained in 46CSR1 and the groundwater quality standards are contained
in 46CSR12.
The location of potential receptors can be ascertained in a number of ways, such as:
1. A search of state and local records for the locations of private and public
drinking water wells within the expected path of plume migration.
2. A request from a public water surveyor for a listing of their service area
within the expected path of plume migration.
3. A survey of streams and rivers within the expected path of plume
migration.
4. Contact the local, county, or state planning boards to determine potential
future land uses of adjacent properties within the expected path of plume
migration.
5. Field survey / resident interviews.
If the contaminant plume is, or will be, migrating onto adjacent properties, the applicant
must demonstrate that either the properties are served by an existing public water supply which
uses surface water or hydraulically isolated groundwater; or the applicant has obtained written
consent from the property owners allowing contaminant migration onto their property. This is
important even if adjacent properties are currently vacant, because 60CSR3 requires
consideration of potential receptors in the reasonably foreseeable future.
If the contaminant plume is expected to intercept surface waters, the groundwater
discharge beyond the sediment/water interface cannot exhibit contaminant concentrations that
7 - 15
would result in violations of standards for surface waters contained in 46CSR1. This can be
determined through one or more of the following techniques:
Install groundwater monitoring wells at the upgradient boundary of the
surface water body.
Model the expected effect of the groundwater discharge using mass balance
modeling techniques.
Other methods/strategies acceptable to the department.
The choice of the method(s) used to assess potential surface water impacts must be
considered on a case by case basis dependent upon site-specific issues, such as the ability to gain
access to offsite properties, the potential for a regional impact or other downgradient sources,
potential upstream sources, seasonal conditions, etc.
7.5.4 Develop a Long-Term Monitoring Plan
A long-term monitoring plan is used to monitor plume migration and to verify that
natural attenuation is ongoing and its rate is sufficient to preclude impact to receptors. This
monitoring plan should include periodic sampling of wells in the different areas of the site, for
example: a) upgradient of the source area in a non-contaminated area; b) in the source area; c)
downgradient of the source area in the dissolved contaminant plume; e) downgradient of the
plume; and (f) surface water collection points. Downgradient compliance monitoring points
need to include one or more monitoring wells at least one year’s advective time of travel
upgradient of any potential receptor, and at least one monitoring well no farther away from the
leading edge of the contaminated groundwater five years advective travel time. These wells
should be sampled for all of the parameters used to support the natural attenuation strategy for
the site including parent and daughter compounds, dissolved gasses, electron donors and electron
acceptors. Information regarding the long-term monitoring plan, analytical suite, sampling
frequency, etc., is discussed in Wiedemeier, et al, 1995.
7.6 References
7.6.1 Remedy Selection, Contaminant-Specific
A Compendium of Technologies Used in the Treatment of Hazardous Wastes,
EPA/625/8-87/014, US Environmental Protection Agency, Center for
Environmental Research Information, Cincinnati, OH, 1987.
A Guide to the Assessment and Remediation of Underground Petroleum Releases.
Publication 1628, American Petroleum Institute, Washington, DC, 1989.
7 - 16
Guidance on Remedial Actions for Superfund Sites with PCB Contamination,
EPA/540/6-90/007, US Environmental Protection Agency, Office of Solid Waste
and Emergency Response, Washington, DC, 1990.
Presumptive Remedies: Site Characterization and Technology Selection for
CERCLA Sites with Volatile Organic Compounds in Soils. EPA/540/F-93/048,
US Environmental Protection Agency, Office of Solid Waste and Emergency
Response, Washington, DC, 1993.
Technology Selection Guide for Wood Treater Sites. Publications 9355.0-46FS
and 9355.0-46, US Environmental Protection Agency, Office of Solid Waste and
Emergency Response, Washington, DC, 1993.
7.6.2 Remedy Selection, Technology-Specific
Engineering Bulletin: Soil Washing Treatment. EPA/540/2-90/017, US
Environmental Protection Agency, Office of Emergency and Remedial Response,
Washington, DC and Office of Research and Development, Cincinnati, OH, 1990.
Engineering Bulletin: Thermal Desorption Treatment. EPA/540/2-91/008, US
Environmental Protection Agency, Office of Emergency and Remedial Response,
Washington, DC and Office of Research and Development, Cincinnati, OH, 1991.
Engineering Bulletin: In-Situ Steam Extraction Treatment. EPA/540/2-91/005,
US Environmental Protection Agency, Office of Emergency and Remedial
Response, Washington, DC and Office of Research and Development, Cincinnati,
OH, 1991.
Engineering Bulletin: In-Situ Soil Vapor Extraction Treatment. EPA/540/2-
91/006, US Environmental Protection Agency. Office of Emergency and
Remedial Response, Washington, DC and Office of Research and Development,
Cincinnati, OH, 1991.
Engineering Bulletin: Slurry Biodegradation. EPA/540/2-90/016, US
Environmental Protection Agency. Office of Emergency and Remedial Response,
Washington, DC and Office of Research and Development, Cincinnati, OH, 1990.
Handbook for Stabilization/Solidification of Hazardous Wastes. EPA/540/2-
90/001, US Environmental Protection Agency, Office of Emergency and
Remedial Response, Washington, DC, 1986.
Engineering Bulletin: Mobile/Transportable Incineration Treatment. EPA/540/2-
90/014, US Environmental Protection Agency. Office of Emergency and
Remedial Response, Washington, DC and Office of Research and Development,
Cincinnati, OH, 1990.
7 - 17
Handbook on In-Situ Treatment of Hazardous Waste-Contaminated Soils.
EPA/540/2-90/002, US Environmental Protection Agency, Risk Reduction
Engineering Laboratory, Cincinnati, OH, 1990.
Engineering Bulletin: Chemical Dehalogenation Treatment: APEG Treatment.
EPA/540/2-90/015, US Environmental Protection Agency, Office of Emergency
and Remedial Response, Washington, DC, and Office of Research and
Development, Cincinnati, OH, 1990.
Engineering Bulletin: Chemical Oxidation Treatment. EPA/540/2-91/025, US
Environmental Protection Agency, Office of Emergency and Remedial Response,
Washington, DC, and Office of Research and Development, Cincinnati, OH,
1990.
Ground Water and Leachate Treatment Systems. EPA/625/R-94/005, US
Environmental Protection Agency, Office of Research and Development,
Washington, DC, 1995.
Remediation of Contaminated Sediments. EPA/625/6-91/028, US Environmental
Protection Agency, Office of Research and Development, Washington, DC, 1991.
Pump-and-Treat Ground Water Remediation. EPA/625/R-95/005, US
Environmental Protection Agency, Office of Research and Development,
Washington, DC, 1996.
Land Use in the CERCLA Remedy Selection Process. OSWER Directive No.
9355.7-04, US Environmental Protection Agency, Office of Solid Waste and
Emergency Response, Washington, DC, 1995.
7.6.3 Remedy Evaluation
Remediation Technologies Screening Matrix and Reference Guide. EPA/542/B-
93/05, US Environmental Protection Agency, Office of Solid Waste and
Emergency Response, Washington, DC, 1993.
Technology Screening Guide for Treatment of CERCLA Soils and Sludges.
EPA/540/2-88/004, US Environmental Protection Agency, Office of Solid Waste
and Emergency Response, Washington, DC, 1988.
Guidance for Conducting Remedial Investigations and Feasibility Studies Under
CERCLA, Interim Final. EPA/540/G-89/004, OSWER Directive 9355.3-01, US
Environmental Protection Agency, Office of Solid Waste and Emergency
Response, Washington, DC, 1988.
Guidance on Conducting Non-Time Critical Removal Actions Under CERCLA.
EPA/540/R-93/057, US Environmental Protection Agency, Office of Emergency
and Remedial Response, Washington, DC, 1993
7 - 18
Summary of Treatment Technology Effectiveness for Contaminated Soil.
EPA/540/2-89/53, US Environmental Protection Agency, Office of Emergency
and Remedial Response, Washington, DC, 1991.
Superfund Engineering Issue: Issues Affecting the Applicability and Success of
Remedial/Removal Incineration Projects. EPA/540/2-91/004, US Environmental
Protection Agency, Office of Emergency and Remedial Response, Washington,
DC, and Office of Research and Development, Cincinnati, OH, 1991.
Guidance on Remedial Actions for Contaminated Ground Water at Superfund
Sites. EPA/540/G-88/003, US Environmental Protection Agency, Office of
Emergency and Remedial Response, Washington, DC, 1988.
7.6.4 Electronic Databases
US Environmental Protection Agency RREL Treatability Database. Computer
disk available from Risk Reduction Engineering Laboratory, Cincinnati, OH,
1990.
Vendor Information System for Innovative Treatment Technologies (VISITT).
US Environmental Protection Agency, Office of Solid Waste and Emergency
Response, PO Box 42419, Cincinnati, OH, 45242-0419.
Clean-up Information Bulletin Board System (CLU-IN). US Environmental
Protection Agency, http://www.clu-in.com.
7.6.5 Cost Analysis / Economics
Blank, Lehland T. and Anthony Tarquin. Engineering Economy. 3rd
ed.
McGraw-Hill. New York. 1989.
Collier, Courtland A. and William B. Ledbetter. Engineering Cost Analysis.
Harper and Row Publishers. New York. 1982.
Newnan, Donald G. Engineering Economic Analysis. 3rd
ed. Engineering Press,
Inc., San Jose, CA. 1988.
Fabrycky, W. J. and G. J. Thuesen. Economic Decision Analysis. 2nd
ed.
Prentice-Hall, Inc., Englewood Cliffs, NJ. 1980.
7.6.6 Natural Attenuation
ASTM Designation: D4448-85a, 1922. Standard Guide for Sampling
Groundwater Monitoring Wells. In: ASTM Standards on Groundwater and
Vadose Zone Investigations: Drilling, Sampling, Well Installation and
Abandonment Procedures (1996), pp. 50-63.
7 - 19
ASTM Designation: RENE, 1996. ASTM Guide for Remediation by Natural
Attenuation.
Bioremediation of Chlorinated Solvents Consortium of the Remediation
Technologies Development Forum (RTDF), 1996. Guidance Handbook on
Natural Attenuation of Chlorinated Solvents, http://www.rtdf.org.
Buscheck, T. E., and C. M. Alcantar, 1995. Regression Techniques And
Analytical Solutions To Demonstrate Intrinsic Bioremediation. In: Proceedings
of the 1995 Battelle 3rd
International In Situ and On-Site Bioreclamation
Symposium, San Diego, CA., April, pp. 109-116.
Domenico, P.A., 1987. An Analytical Model For Multidimensional Transport Of
A Decaying Contaminant Species, J Hydro, 91:49-58.
Feenstra, S., J. A. Cherry, and B.L. Parker, 1996. Conceptual Models For The
Behavior Of Dense Non-Aqueous Phase Liquids (DNAPLs) In The Subsurface.
In: Dense Chlorinated Solvents and Other DNAPLs in Groundwater. J. F.
Pankow and J. A. Cherry (eds.), Waterloo Press, Portland, Oregon.
Howard, P.H., R.S. Boethling, W.F. Jarvis, W.M. Meyland, and E.M.
Michalenko, 1991. Handbook of Environmental Degradation Rates, Lewis
Publishers, Chelsea, MI.
Newell, C.J., J.W. Winters, H.S. Rifai, R.N. Miller, J. Gonzales, and T.H.
Wiedemeier, 1995. Modeling Intrinsic Remediation With Multiple Electron
Acceptors: Results Form Seven Sites. In: Proceedings of the Petroleum
Hydrocarbons and Organic Chemicals in Groundwater Conference, Houston, TX,
November, National Groundwater Association, pp. 33-48.
Newell, C.J., R.K. McLeod, and J.R. Gonzales, 1996. BIOSCREEN Natural
Attenuation Decision Support System, Version 1.3, US Air Force Center for
Environmental Excellence, Brooks AFB, San Antonio, TX.
Rifai, H.S., P. B. Dedient, R.C. Borden, and J.F. Haasbeek, 1987. BIOPLUME
II-Computer Model Of Two-Dimensional Transport Under The Influence Of
Oxygen Limited Biodegradation In Groundwater, User’s Manual, Ver. 1.0, Rice
University, Houston, TX.
Rifai, H.S., R.C. Borden, J.T. Wilson, and C.H. Ward, 1995. Intrinsic
bioattenuation for subsurface restoration. In: Proceedings of the 1995 Battelle 3rd
International In Situ and On-Site Bioreclamation Symposium, San Diego, CA,
April, pp. 1-29.
US Environmental Protection Agency (USEPA) 1997. Use of Monitored Natural
Attenuation at Superfund, RCRA Corrective Action, and Underground Storage
Tank Sites. OSWER Directive 9200.4-17, Office of Solid Waste and Emergency
Response. Washington, DC, November.
7 - 20
Wiedemeier, T.H., J.T. Wilson, D.H. Kampbell, R.N. Miller, and J.E. Hansen,
1995. Technical Protocol For Implementing Intrinsic Remediation With Long-
Term Monitoring For Natural Attenuation Of Fuel Contamination Dissolved In
Groundwater. San Antonio, TX: US Air Force Center for Environmental
Excellence.
Wiedemeier, T.H., M.A. Swanson, D.E. Moutoux, J.T. Wilson, D.H. Kampbell,
J.E. Hansen, and P. Haas, 1996a. Overview Of The Technical Protocol For
Natural Attenuation Of Chlorinated Aliphatic Hydrocarbons In Groundwater
Under Development For The US Air Force Center for Environmental Excellence,
Symposium on Natural Attenuation of Chlorinated Organics in Groundwater,
Dallas, TX, pp. 35-39.
Wiedemeier, T.H., M.A. Swanson, J.T. Wilson, D.H. Kampbell, R.N. Miller, and
J.E. Hansen, 1996b. Approximation Of Biodegradation Rate Constants For
Monoaromatic Hydrocarbons (BTEX) In Groundwater, Groundwater Monitoring
and Remediation, pp. 186-194.
Wiedemeier, T.H., M.A. Swanson, D.E. Moutoux, J.T. Wilson, D.H. Kampbell,
J.E. Hansen, P. Haas, and F.H. Chapel, 1996C. Technical Protocol For Natural
Attenuation Of Chlorinated Solvents In Groundwater, US Air Force Center for
Environmental Excellence, San Antonio, TX.
Wilson, J.T., D.H. Kampbell, and J.W. Weaver, 1996. Environmental Chemistry
And The Kinetics Of Biotransformation Of Chlorinated Organic Compounds In
Groundwater, EPA Symposium on Natural Attenuation of Chlorinated Organics
in Groundwater, Dallas, TX, pp. 124-127.
Zheng, C. 1990. MT3D: A Modular Three-Dimensional Transport Model for
Simulation of Advection, Dispersion and Chemical Reaction of Contaminants in
Groundwater Systems, Waterloo Hydrogeologic, Inc., Waterloo, Ontario, Canada.
8 - 1
8.0 REMEDIAL ACTION WORKPLAN
8.1 Purpose
The purpose of this workplan is to describe the remedy to be employed at a site and a
statement of work and schedule for the remediation. Where various remedial alternatives were
considered, the workplan should address the rational for remedy selection which includes but is
not limited to a description of information used in the decision making process, a discussion of
potential remediation alternatives, and any uncertainty or risks which exist.
8.2 Information Required
The workplan must address, directly or by reference, the investigation conducted by the
applicant to further determine the nature and extent of actual or threatened releases that led to the
preparation of the workplan. It will also describe assessments to be performed to further
characterize the site or contaminants before remedial action is initiated. Risk assessment
conducted to show the appropriateness of remedy selection should be documented in detail as
described in Sections 5.0 and 6.0. The statement of work to accomplish the remediation and an
implementation schedule must be submitted and must be carried out in accordance with the risk
protocol and remediation standards in the rule (§60-3-9). The sampling plan to be implemented
following remediation to determine the adequacy of the remediation program must also be
addressed in the workplan.
8.3 Remediation Standards
Remediation standards may be attained through one or more remediation activities that
can include treatment, removal, engineering or institution controls, natural attenuation and
innovative or other demonstrated measures. Remediation standards are to be defined where
appropriate for soil, sediment, surface water, and groundwater (§60-3-9.7.d.1). These standards
are to be established using the following considerations as described in §60-3-9.
potential receptors of concern based on the current and reasonably anticipated
use of the site;
site-specific sources of contaminants;
natural environmental conditions affecting the fate and transport of
contaminants, such as natural attenuation processes, as determined by
approved scientific methods; and
institutional and engineering controls.
The remediation standards or combination of standards selected by each applicant for the
protection of human health (§60-3-9.1.a) and the ecological receptors (§60-3-9.1.b) must be
described including the rational for the selection of each standard.
8 - 2
8.4 Remediation Measures
Specific remediation measures to be implemented for the site must be addressed. These
may include treatment, removal, engineering or institutional controls, natural attenuation and
innovative or other demonstrated measure which may be utilized should be defined.
8.4.1 Selection of Alternatives
Where various remedial alternatives were considered, the remedial workplan must
address the remedial action selected to achieve the goal of cost effective protection of human
health and the environment. Describe:
the effectiveness of the remedy in protecting human health and the
environment;
the reliability of the remedial action in achieving the standards over the long
term;
the short term risks to the affected community, those engaged in the remedial
action effort, and to the environment;
the acceptability of the remedial action to the affected community;
the implementability and technical practicability of the remedial action from
an engineering perspective;
the cost effectiveness of the action; and
the net environmental benefits of the action.
8.4.2 Natural Attenuation
Where the remedy selected is based upon natural processes of degradation and
attenuation of contaminants, the remedial workplan must include a description of relevant site-
specific conditions, including written documentation of projected groundwater use in the
contaminated area based on current state or local government planning efforts; the technical
basis for the request; and any other information requested by the Director. The applicant must
also demonstrate that all conditions described in §60-3-9.9 of the rule have been satisfied (§60-3-
9.9a - §60-3-9.9i).
8.4.3 Uncertainty or Risks
The remedial workplan will include a discussion of any risk or uncertainty associated
with selection and implementation of remedial alternatives. It will fully describe any
assumptions made in the selection of remediation alternatives and the reason that assumptions
8 - 3
are acceptable and defensible. The workplan will also describe the risks and uncertainties
associated with remediation and defend the acceptability of the risks.
8.5 Remediation
The following items which provide details of the remediation activity, must be included
in the Remedial Action Workplan:
statement of work to be conducted to accomplish the proposed remediation;
schedule for completion of remedial actions;
verification sampling plan to determine the adequacy of the remediation; and
any additional information or supporting plans.
8.6 Submittal
Workplans and reports required by the VRA shall be submitted to the Director by the
applicant or the applicant’s LRS. The Director may approve or disapprove the workplan within
30 days of receipt based on quality and completeness. Disapproval of a workplan must be
communicated to the applicant within 5 days of the disapproval with a list of reasons for
disapproval and additional information needed. If a workplan is disapproved, the applicant must
either resubmit the workplan or formally terminate the Voluntary Remediation Agreement. If
workplans are not approved or disapproved with the 30 days, the workplan will be deemed
approved. Time limitations on the submission and approval of the Remedial Action Workplan
are to be set out in the VRA.
9 - 1
9.0 FINAL REPORT
When all applicable standards developed for the site have been met and all requirements
of the VRA have been satisfied, the final report may be prepared and submitted. Sites may be
subdivided for the purpose of preparing the final report.
9.1 Contents
The final report shall include:
all data and information needed to document and verify that all applicable
standards have been met and that all activities specified in the Voluntary
Remediation Agreement have been completed;
the site location including the street address, legal description (including lot
and block numbers), and site location map;
the names, addresses, telephone numbers, and facsimile transmission numbers
for the current owners and operators of the site, the owners and/or operators
conducting the remediation (if different), and the licensed remediation
specialist; and
a description of the ongoing work, such as site cover or treatment system
operation and maintenance, groundwater or surface water monitoring, and
planned activities and schedules for the aforementioned.
9.2 Appendices
The following information should be attached as appendices to the final report:
copies of appropriate documents confirming that the institutional controls
such as deed restrictions or land use covenants have been properly recorded if
they are part of the remediation program (including a site map showing the
area(s) subject to the institutional controls) and
supporting documentation, such as sample collection records, field monitoring
data, laboratory reports, relevant correspondence, chain of custody forms, and
permits.
9.3 Additional Documentation
Earlier reports, plans, and/or other relevant documents may be incorporated into the final
report by reference providing that a complete bibliographic reference is furnished and that the
items have been previously submitted to the Division. The use of maps, drawings, photographs,
tables, and other aids to visualization and data presentation is encouraged.
9 - 2
9.4 Certification
The completeness and accuracy of the final report will be certified, in writing, by an
authorized agent of the applicant and by the Licensed Remediation Specialist. The form of the
certification shall be as follows:
I hereby certify that the information presented in this report is, to the best of my
knowledge and belief, true, accurate, and complete, having been prepared under a
system and organization designed to produce true, accurate, and complete
information.
A - 1
APPENDIX A: CHECKLIST FOR CONCEPTUAL SITE MODEL DEVELOPMENT
This checklist is to be submitted with the application and should incorporate information
available at the time of submittal.
Step 1. Define Site Characteristics
1.1 Check geologic setting characteristics that apply (“yes” situation found at/near site)
_ fractured rock _ fill material _ none as listed above
_ alluvial aquifer _ karst
1.2 Depth to ground water: ________ feet.
Is the underlying aquifer
_ confined _ perched _ unconfined _ don’t know
1.3 General direction of ground water flow across the site:
_ NW _ N _ NE _ E _ SE _ S _ SW _ W
1.4 Local surface water bodies:
_ wetlands _ spring/seep _ stream _ river _ lake _ pond/impoundment
Surface water distance(s) from site ______ miles(s)
1.5 Are there known discharge points/springs from the underlying aquifer?
_ yes _ no
Distance from site to known discharge points ______ miles(s)
1.6 Determine average soil characteristics for usual site conditions:
1. Soil type (check appropriate)
_ clay _ silt _ sand _ gravel
2. Is the average soil or water pH less than or equal to 3 or greater than or equal to 9?
_ yes _ no
1.7 Have any of the following activities occurred at the site?
_ surface mining _ deep mining _ injection or extraction wells
_ monitoring wells
Step 2. Define the Contaminant Characteristics
2.1 Basic Contaminant Information
Contaminant Category Petroleum Metals Other Inorg. SVOCs VOCs PCBs Pests. Other
Surface Impoundments _ _ _ _ _ _ _ _
Above ground drums _ _ _ _ _ _ _ _
Buried drums _ _ _ _ _ _ _ _
AST _ _ _ _ _ _ _ _
UST _ _ _ _ _ _ _ _
Piles _ _ _ _ _ _ _ _
Landfill _ _ _ _ _ _ _ _
Open dump _ _ _ _ _ _ _ _
Other _______ _ _ _ _ _ _ _ _
A - 2
2.2 Indication of Suspected Contamination
_ unusual level of vapors _ erratic behavior of product dispensing equipment
_ release detection results indicate a release _ discovery of holes in a storage tank
_ spill/release _ other (specify) ___________________________
2.3 Visible evidence of contamination (check all that apply):
_ contaminant stained or contaminant saturated soil or backfill
_ ponded contaminants
_ free products or sheen on ponded water
_ free product or sheen on the groundwater surface
_ free product or sheen surface water
_ visual evidence of stressed biota (fish kills, stressed vegetation, etc.)
_ visible presence of oil, tar, or other non-aqueous phase contaminant >=1,000 sq. ft
_ other (specify) ____________________
2.4 Are there any interim remedial actions that have or will take place?
_ yes _ no (if “yes”, fill out 2.5)
2.5 Interim remedial actions (check all that apply): Planned Initiated Completed Not Applicable
Regulated substance removed from storage tanks _ _ _ _
Containment of contamination _ _ _ _
Contaminated soil excavated _ _ _ _
Free product recovered _ _ _ _
Temporary water supplies provided _ _ _ _
Other (specify) ___________________ _ _ _ _
Step 3. Define Exposure Media and Transport Pathways
3.1 Identify media affected (or potentially affected by contaminants:
Contaminant
_________ _ air _ groundwater _ surface water _ soil _ sediments _ biota
_________ _ air _ groundwater _ surface water _ soil _ sediments _ biota
_________ _ air _ groundwater _ surface water _ soil _ sediments _ biota
3.2 Identify contaminant release mechanisms (check all that apply):
Contaminant
_________ _ leaching _ volatilization _ fugitive dust _ erosion / runoff
_________ _ leaching _ volatilization _ fugitive dust _ erosion / runoff
_________ _ leaching _ volatilization _ fugitive dust _ erosion / runoff
3.3 Groundwater use:
Is the groundwater connected to or part of an aquifer that serves as a source of
drinking water?
_ yes _ no (if “yes”, groundwater is of concern)
Are there reasonably expected future groundwater uses based on state or local
planning?
_ yes _ no (if “yes”, groundwater is of concern)
A - 3
3.4 Local water supplies:
Industrial / municipal _ surface _ well
Residential _ surface _ well
Agricultural _ surface _ well
Water supply distance from site: _____________miles(s)
3.5 Local surface water (check all that apply):
Use
Domestic supply _
Recreation _
Irrigation/stock watering _
Industrial supply _
Not currently used _
Fisheries _
Other __________ _
3.6 Local groundwater use (check all that apply):
Use
Domestic supply _
Irrigation / stock watering _
Industrial supply _
Not currently used _
Other ___________ _
3.7 Check if the following exposure pathways are applicable under foreseeable use of the
site:
_ soil ingestion _ surface water ingestion
_ inhalation of soil particles/vapors _ dermal contact with surface water
_ dermal contact with soil _ groundwater ingestion
_ consumption of plants _ consumption of terrestrial animals
_ consumption of aquatic organisms _ other ____________
_ inhalation of vapors released from groundwater
B - 1
APPENDIX B: DETERMINING BACKGROUND CONCENTRATIONS
B.l Choosing Sample Locations
Background concentrations must be determined by sampling areas not affected by site
contamination. The selection of a sampling area for background samples is a site-specific
decision. The samples should be collected in an unbiased fashion (i.e., not from any areas that
are expected to have particularly high or low concentrations). To the extent practical in selecting
locations for samples to determine the background levels, the following criteria should be
considered as appropriate for soils, sediments, and groundwater. Additional criteria for each
media are given below.
1. The samples must be taken up-wind/up-stream and/or up-gradient from
suspected or known contamination from the site under study or other sites
that are suspected or known to be contaminated.
2. The samples should be taken from areas beyond the contamination
boundary but within 5 miles.
3. Samples should be taken from areas that have the same basic
characteristics as the medium of concern at the site. The samples should
be taken from the same geologic strata as is found at the site.
4. Depth intervals similar to that from which samples will be collected at the
site are also to be analyzed. More than one sample at each depth interval
and medium within a stratum should be collected.
The same sampling and analysis procedures must be used for the proposed background
areas as were used on the site. To the extent practical, the applicant should include a complete
and detailed description of the anthropogenic impact history of the areas selected, the basis for
concluding anthropogenic contaminants in these areas are not site-related and a justification for
their selection as representative of anthropogenic impacts to the site.
B.1.1 Soils
Areas chosen to represent background should be of the same soil type or geologic
stratum, and should have no large-scale spatial variations. If the site exhibits large-scale spatial
variations, it should be subdivided into more homogeneous subsections and matching
background areas should be found for each subsection.
B.1.2 Sediments
For sediments, background samples should be matched for particle size distribution, acid
volatile sulfides, total organic carbon, and water content; this may require identifying matched
watersheds, or sediment sampling sites sufficiently far downstream to dilute any site influence on
B - 2
sediment contaminant levels. If the site exhibits large-scale spatial variations, it should be
subdivided into more homogeneous subsections and matching background areas should be found
for each subsection. Where closely matched sediments cannot be found, the impact should be
described in the uncertainty analysis.
B.1.3 Groundwater
Determination of background in groundwater is usually based on comparisons with
upgradient wells of similar geologic setting not affected by the site.
B.2 Choosing Sample Size
The minimum number of samples required to establish background levels is site-specific,
and, although the methods are not media-specific, samples required may vary for soil vs.
groundwater. Gilbert (1993) suggests 10 or more as a “reasonable number” of background
measurements, but does not give any justification for this number. Ohio EPA (1991) proposes 7
samples for an initial survey of background, based on the assumption that the desired confidence
and the relative standard deviation are equal. Both of these guidelines are only “rules of thumb”.
The number of samples required should depend on the desired standard error on the mean and on
the variance of the background distribution. If the background concentrations are highly
variable, then more samples will be required to achieve a particular standard error on the mean.
EPA 1989 and 1996 describe in detail the statistical parameters for choosing sample sizes.
B.3 Report Requirements for Site-Specific Background
The applicant must identify how site background was established and for which media
(soil, sediments, groundwater, and/or surface water). The investigative methods used must be
identified (e.g. monitoring wells, soil borings, water samples). The sample locations need to be
shown on a map (enclosed with the results). The tabular presentation of sample results will
facilitate review. The presentation of the results will include, but is not limited to:
1. Description of media sampled (e.g., soil, water, sediments)
2. List of background investigation analytical methods
3. Description of methods used in collecting background data (e.g., soil
borings, existing literature.
4. Background sample location map and rationale for sample locations
5. Description of sampling procedure and sampling equipment used
6. Description of monitoring well and/or soil boring installations (if
appropriate)
B - 3
7. Description of field screening procedures used and tabulated results of the
field screening procedures.
8. Description of blanks and controls used
9. Presentation of background data in tabular form (media, parameters,
concentrations, depth of samples, etc.
10. Statistical evaluation of background results
11. Documentation procedures, waste disposal data and manifests, and chain-
of-custody forms
All the samples taken for the intent of determining background levels are to be included
in the final report. Statistical analyses must include all data that are not known to be in error, and
the source of data quality errors must be described fully for any data which are excluded. The
sampling protocols must be the same as will be applied to the samples collected at the site.
B.4 Statistical Methods for Comparison of Site Concentrations With Background
A number of statistical methods have been recommended for comparing site and
background concentrations. These methods are independent of the media sampled (soil,
sediment, groundwater). These methods include the following:
Comparisons of distributions of site and background concentrations (e.g., quantile
test, Wilcoxon rank sum test),
Comparisons of site and background means (e.g., t-test), and
Comparisons of high concentrations (e.g., hot measurement comparison, using
95% upper tolerance limit on 95th
percentile to represent hot measurement).
A number of documents describe the various methods, such as USEPA (1989), ASTM
(1993), Ohio EPA (1991), and Gilbert (1993, 1987). The statistical tests described in these
sources, like most statistical tests, are designed to show that two distributions (or two quantities
representing distributions) are different. Failure to show that two distributions are different,
however, does not necessarily imply they are the same. If the test fails to show a statistically
significant difference, there are two possibilities:
1. The distributions are the same, or
2. The distributions are different, but the test did not have enough power, i.e.,
there were not enough samples to demonstrate a statistically significant
difference.
Using these kinds of tests, there is no way to distinguish between these two possibilities.
Consequently, these tests cannot show that two distributions are the same.
B - 4
This guidance discusses two methods of comparing site data to background. In order to
determine whether the site data fall within the range of background concentrations, it is most
appropriate to use both a comparison of means and a comparison of individual site
concentrations with an upper tolerance limit (UTL) background concentration. Both
comparisons are recommended because failure of either alone can indicate that some portion of
the site concentrations exceed background. Figures B-1 and B-2 shows sample distributions for
site and background. Figure B-1 illustrates a situation where the site mean is less than the
background mean, but greater than 5% of site concentrations exceed background in the upper
“tail” of the distribution. Figure B-2 illustrates a situation where the site mean exceeds the
background mean, but less than 5% of site concentrations exceed background in the upper tail of
the distribution. These represent situations where site concentrations may exceed background
even though one of the statistical tests is passed.
Figure B-1
Site mean < Background mean
Background 95th percentile < Site 95th percentile
0 10 20 30 40 50 60 70 80
Concentration (mg/kg)
Pro
ba
bili
ty
Site
mean
Background mean
Site 95th pctile
Background
95th pctile
B - 5
Figure B-2
Background mean < Site mean
Site 95th percentile < Background 95th percentile
0 10 20 30 40 50 60 70 80
Concentration (mg/kg)
Pro
ba
bili
ty
Site mean
Background
mean
Site 95th
pctile
Background
95th pctile
The following terminology is used in this guidance:
Sample mean. The sample mean is the arithmetic average calculated from a sample
consisting of a number of observations.
True mean. The true mean is the mean of the underlying distribution from which the
sample is drawn. The true mean is unknown, but it can be estimated by the sample
mean. The precision of this estimate improves as the sample size increases.
Standard error. The standard error on the mean is a measure of the uncertainty in
the estimate of the true mean. The standard error is defined as (SD/ N , where SD
is the sample standard deviation and N is the number of observations.
Distribution of the mean. The distribution of the mean describes the uncertainty in
the sample mean as an estimate of the true mean. There are many plausible values for
the true mean, which is unknown, and probability of each of these values is given by
the distribution of the mean. The spread of this distribution is determined by the
standard error on the mean.
B.4.1 Comparison of Means
A two tiered approach is recommended here. At sites for which both site and background
concentrations are well characterized, so that there is little uncertainty in the two means, the Tier
B - 6
1 method may be used. As discussed in Section B.5.1.1, this method is a simple comparison of
means, where complicated statistical calculations are not required. If background concentrations
are well characterized, but site concentrations are not as well characterized, so that there is
significant uncertainty in the site mean, the Tier 2 method is applicable. This method, presented
in Section B.5.1.2, is more complicated but can be used in a wider range of situations.
Both methods depend on the definition of an acceptable difference, represented by the
symbol , between the true site mean and the true background mean. Selection of an appropriate
value for is discussed in Section B.5.1.4. Section B.5.1.5 discusses how all of the methods
encourage more complete characterization of both site and background concentrations. A flow
chart for comparing the site mean to the background mean is provided in Figure B-3.
B.4.1.1 Tier 1 Method for Comparing Means
The Tier 1 method depends on two critical assumptions: both the site mean and the
background mean are known precisely enough that it is not necessary to consider uncertainty in
the means. In other words, it is assumed that the true means are equal to the sample means. If
these assumptions are made, then the appropriate test is a simple comparison of sample means.
If the site mean is less than or equal to the background mean plus , then the two means are
effectively the same, so site and background concentrations can be considered equivalent.
For the two assumptions to be justified, the standard errors on both the site mean and the
background mean must be small compared to (e.g., both standard errors should be less than
/55).
5Standard error less than /5 is used throughout this guidance as an example of a reasonable criterion for ignoring the uncertainty in
the mean. A different criterion could be used without changing the ideas presented here.
B - 7
FIGURE B-3
COMPARISON OF SITE MEAN TO BACKGROUND MEAN
Calculate Background
Sample Statistics:
Mean SD
SE = SD / N
Select as 20-30% of
Background Mean
Is
Background
SE
/ 5?
Determine Distribution of Site
Data: Normal or
Lognormal? Do data fit either distribution
with
r2 0.8?
Calculate Site Sample Statistics:
Mean DS
SE=SD N
Is Site SE
/ 5?
Tier I Method to Compare Means
Continue with UTL Comparison
Re-evaluate Background Data:
(1) Ensure that all data are from the same population,
or
(2) Collection additional background samples, or
(3) Re-evaluate definition of .
Re-evaluate Site Data:
(1) Ensure that all data are from the same population, or
(2) Collection additional samples
Tier 2 Method
to Compare Means
Date
Normally
Distributed?
Use t-statistic
Use H-statistic
No
No
Yes
Yes
No
Yes No
B - 8
Otherwise, the true site mean could be substantially higher than the sample mean, or the
true background mean could be substantially lower than the sample mean, or both. In either
case, the simple comparison of the sample means would not show conclusively that the true
means are effectively the same. Consequently, if the standard errors on the means are not small
compared to , the Tier 1 method should not be used.
For example, consider the site and background data sets described by the summary
statistics in Table B-1.
Table B-1: Summary Statistics for Example Data Sets
Site Data
Background
Data
N 100 25
Sample Mean (ppm) 27 25
Sample Standard Deviation (ppm) 10 5
Standard Error (ppm) 1.0 1.0
If , the acceptable difference between the site and background means, is defined as 20%
of the background mean (5 ppm, in this case), then both the site and background data sets meet
the criterion that the standard error is less than or equal to /5. In this case the site mean is less
than the background mean plus (i.e., 25 + 5 = 30, 27 <30), so the conclusion is that the site and
background means are equivalent for risk assessment purposes.
B.4.1.2 Method for Comparing Means
The Tier 2 method requires less restrictive assumptions than Tier 1, but the statistical test
is more complicated as a result. This method depends on the assumption that the background
mean is known precisely enough that it is not necessary to consider the uncertainty in the mean
(i.e., the standard error on the background mean is less than /5). The site mean, however, is
represented by a probability distribution that incorporates the uncertainty. This is necessary
when the standard error on the site mean is not small compared to (i.e., the standard error on
the site mean exceeds /5).
In order to show that the site mean is effectively the same as the background mean, the
following probability (P*) must be calculated:
P* = P[s (b + )]
where:
P* is the probability that the true site mean is less than or equal to the true background
mean plus ,
s is the true site mean, represented by a probability distribution,
b is the true background mean, assumed to bee known exactly, and
is the acceptable difference between s and b.
B - 9
If the value of P* is sufficiently high (e.g., 80%), then the site and background means are
shown to be effectively the same.
P* can be calculated because it is assumed that b is known exactly and the distribution of
s is known. If the site data are normally distributed, or if the central limit theorem holds6, then
the site mean follows the t distribution. If the site data are lognormally distributed and the
central limit theorem does not hold (data too skewed/not enough observations), then the H-
statistic must be used to determine the distribution of the site mean (Land, 1975). In either case,
it is possible to determine the value of P* by calculating the necessary value of t or H and using a
look-up table to determine the level of confidence that value corresponds to (see End Notes 1 and
2). End Note 3 discusses how to determine if data are normally or lognormally distributed.
As an example, consider the site and background data sets described by the summary
statistics in Table B-2. The background data set here is identical to the one in Table B-1, but the
site data set has fewer samples and a larger standard deviation. Assuming a of 5 ppm, the Tier
1 method would not be applicable in this case because the standard error on the site mean is not
small compared to .
Table B-2: Summary Statistics for Example Data Sets
Site Data
Background
Data
N 20 25
Sample Mean (ppm) 27 25
Sample Standard Deviation (ppm) 15 5
Standard Error (ppm) 3.4 1.0
If the central limit theorem applies, P* can be calculated from the t-statistic, as explained
in End Note 1. The value of the t-statistic corresponding to the critical value of b + can be
calculated as:
t
x N
SD
b s s
s
where:
xs is the sample mean calculated from the site data (27 ppm),
SDs is the sample standard deviation calculated from the site data (15 ppm),
Ns is the number of observations in the site sample (20),
t is the t-statistic,
b is the true background mean, assumed to be exactly (25 ppm), and
is the acceptable difference between the true site mean and the true background mean
(5 ppm)
6The central theorem states that the distribution describing the uncertainty in the mean of a sample drawn from any
distribution approaches normality as the number of observations increases. In general, when the sample variance is unknown, the
sample mean follows the t distribution. However, if the distribution from which the observations are drawn is sufficiently skewed, and there are an insufficient number of observations, the sample mean will not be t-distributed.
B - 10
From this equation, t is 0.89. For 19 degrees of freedom (N-1), this value of t
corresponds to the 81st percentile from the distribution of the site mean. As a result, P* is 0.81.
In other words, there is an 81% probability that the true site mean is less than or equal to the true
background mean plus . If the required level of confidence is 80%, then it can be concluded
that the site and background means are effectively the same.
B.4.1.3 Selection of
All of the methods discussed here depend on the selection of an appropriate . The
choice of is a risk management decision. One possibility is to define , which should be
chemical-specific, as a percentage of the background mean. For example, if is 20% of the
background mean, then an acceptable site mean would be no more than 20% higher than the
background mean.
If is too small, then a very large data set would be required to show that the means are
effectively the same with any reasonable degree of confidence. For example, consider the case
in which = zero. If the site and background data sets are drawn from the same distribution (so
that the means are identical), then it would never be possible to show that s b + with
greater than 50% confidence (i.e., P* 50%). If 80% or 90% confidence is required, then
must exceed zero.
B.4.1.4 Required Characterization of Site and Background Concentrations
Both of the recommended methods encourage more complete characterization of both
site and background concentrations. The Tier 1 method requires that the uncertainty in both the
background and site means be small compared to . This condition can only be met if both site
and background concentrations are well characterized. The number of samples required depends
on the value of and on the variance of the underlying distributions. A distribution with high
variance requires more samples to reduce the uncertainty in the mean.
The Tier 2 method requires that the uncertainty in the background mean be small
compared to , which means that background must be well characterized. In addition, this
method rewards a more complete characterization of the site, which increases the precision of the
estimate of the true site mean. Assuming that site and background are nearly equivalent, P* will
increase as the precision in the estimate of the true site mean increases, showing more
conclusively that the site and background means are effectively the same.
B.4.2 Comparison of Individual Samples to an Upper Tolerance Limit
Individual data points from a site should be compared with a value that represents the
upper end of the range of background concentrations, with the criteria that a large percentage of
them, e.g. 95%, should fall within the range of background. (It would be inappropriate to
compare each data point to the background mean, because as many as 50% of the data points
could exceed this value even if all site data fell within the range of background). The level that
individual data points are compared to is termed an upper tolerance limit (UTL). An upper
B - 11
tolerance limit (UTL) is usually specified as the 95th
percent upper confidence limit on the 95th
percentile of the distribution describing the data, where the 95th
percentile is the value below
which 95% of the data fall. Conceptually, this means that there is a 95 percent certainty, or
probability, that 95 percent of the concentrations fall below the UTL. Or, if multiple sets of
samples are taken from the same area and the 95th
percentile of each sample set is assessed, then
95% of the 95th
percentiles would fall below the UTL. A flow chart for comparison of
individual site data to background is provided in Figure B-4.
B.4.2.1 Calculating the Upper Tolerance Limit on Normally Distributed Data
The upper tolerance limit on a normally distributed data set is calculated with the k
statistic, as described in USEPA (1989) and Gilbert (1987, 1993). The formula is:
UTL x k s
where x is the sample mean, s is the sample standard deviation, and k is the k statistic, which is a
function of sample size, the percentile for which a UTL is to be estimated (95th
in this case), and
the confidence limit on this percentile (95th
% upper confidence limit). Values of the k statistic are
tabulated in USEPA (1989), Table A.4.
B.4.2.2 Calculating the Upper Tolerance Limit on Lognormally Distributed Data
The upper tolerance limit on a lognormally distributed data set is calculated with the k
statistic, as described in USEPA (1989) and Gilbert (1987, 1993):
UTL x k s exp ( )
where x and s are the mean and standard deviation, respectively, of the log-transformed
concentrations, and k is the k statistic, which is a function of sample size, the percentile for which
a UTL is to be estimated (95th
in this case), and the confidence limit on this percentile (95th
%
upper confidence limit). Values of the k statistic are tabulated in USEPA (1989), Table A.4.
B.4.2.3 Estimated Upper Limit for Background
The Ohio EPA (1996) estimates an upper limit for background as the mean plus 2
standard deviations:
UL x sbackground 2
where x is the sample mean and s is the sample standard deviation. When the number of
background samples (N) is greater than 70, use of this formula will yield an upper limit that is
higher (less conservative) than the UTL, since the value of the k – statistic is less than 2 for
N>70.
B - 12
End Note 1 Calculation of P* from t-Statistic
If the central limit theorem applies, the distribution of the site mean can be approximated
by the t distribution. The percentile from this distribution corresponding to the critical value of
b + can be calculated as:
x tSD
Ns
s
s
b
where:
xs is the sample mean calculated from the site data.
SDs is the sample standard deviation calculated from the site data,
Ns is the number of observations in the site sample,
t is the t-statistic
b is the true background mean, assumed to known exactly, and
is the acceptable difference between the true site mean and the true background mean.
All of these quantities are known except for t, which can be calculated as:
t
x N
SD
b s s
s
This value of t can be looked up in a table, for the t distribution with Ns-1 degrees of
freedom, to determine what level of confidence it corresponds to, which gives the value of P*.
B - 13
FIGURE B-4
COMPARISON OF INDIVIDUAL SITE DATA TO BACKGROUND UTL
Determine Distribution of
Background Data
Is N > 70 for Background Data?
Calculate Upper Limit
(UL) for Background
Calculate 95% Upper
Tolerance Limit (UTL) for
Background
Compare Individual Site Data to
Background UTL or UL
Do More Than
5% of Site Data
Exceed
Background
UTL or UL?
Site Data Below Background
Site Data Exceed Background
Compound is a COC
No
Yes
No Yes
B - 14
End Note 2 Calculation of P* from H-Statistic
If the site data re lognormally distributed, the percentile from the distribution of the site
mean corresponding to the critical value of b + can be calculated from the H-statistic (Land,
1975):
eGM
GSD GM H
N
b
ss s
s
loglog log
2
2 1
where:
Log refers to the natural logarithm,
GMs and GSDs are the sample geometric mean and sample geometric standard deviation
calculated from the site data,
Ns is the number of observations in the site sample,
H is the H-statistic,
b is the true background mean, assumed to be exactly, and
is the acceptable difference between the true site mean and the true background mean.
All of these quantities are known except for H, which can be calculated as:
H
N GMGSD
GM
s b s
s
s
12
2
log loglog
log
The resulting H-statistic can be looked up in a table to determine the level of confidence
it corresponds to, which gives the value of P*.
End Note 3 Determining if a Distribution is Normal or Lognormal
In order to determine whether a set of sample data is normally or lognormally distributed,
two plots should be constructed. One is a plot of the concentrations vs. their z score, and the
second is a plot of the logarithms of the concentrations vs. their Z-score (Figures B-5 and B-6).
Data that are normally distributed will plot as a straight line on the first figure, while data that are
lognormally distributed will plot as a straight line on the second figure. A linear regression is
done for each plot to fit a straight line to the data, and the R-squared value (coefficient of
determination) is calculated. The R-squared value is an indication of how well the data fit a
straight line. The R-squared values are compared and the plot with the higher R-squared value is
considered to be the distribution that best describes the data. Most environmental data fit either
a normal or log-normal distribution (Ott, 1990). If the data do not fit either distribution with an
R-squared value of at least 0.70, it may be that: 1) not enough samples were collected, or 2) the
samples may represent different areas of the site (i.e., different spatial distributions) and may
have been inappropriately combined into one data set. In this case it is important to determine
the need for additional sample collection and review the sources of the data before proceeding
with any analysis.
B - 15
The probability plots discussed above can be constructed in Excel by the following
method:
List the sample concentrations in ascending order.
Calculate the natural log of each concentration.
Determine the rank of each concentration.
Determine the cumulative probability for each data point. This is equivalent to
the Rank (n+l).
Determine the Z-score for each data point from its cumulative probability. In
Excel, the Z-score can be calculated using the NORMSINV function:
Z-score = NORMSINV (Cumulative Probability)
Plot the Z-score vs. the sample concentration and the Z-score vs. the log-
transformed concentrations.
B - 16
B - 17
References
ASTM, 1993. ASTM Guide to the Comparison of Hazardous Waste Site and Background Soil
Data
Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. Van Nostrand
Reinhold: New York, New York, 320 pp.
Gilbert, R..O. 1993. Battelle, Pacific Northwest Laboratories, memo to Beverly Ramsey,
describing recommended process for comparison of site data with background concentrations at
the Rocky Flats Plant. July 30.
Land, CE. 1975. Tables of Confidence Limits for Linear Functions of the Normal Mean and
Variance. Selected Tables in Mathematical Statistics. III: 385-419.
Ohio Environmental Protection Agency. 1991. How Clean is Clean Policy, Division of
Emergency and Remedial Response, July 26.
Ohio EPA, 1996. Phase II Property Assessments. Voluntary Action Program, Rule OAC 3745-
300-07. Division of Emergency and Remedial Response. December 16.
Ott, W.R., 1990. A physical explanation of the lognormality of pollutant concentrations. J. Air
Waste Management Assoc. 40:1378:1383.
US Environmental Protection agency (USEPA). 1989. Methods for Evaluating the Attainment
of Cleanup Standards – Volume 1: Soils and Soils Media. Office of Policy, Planning and
Evaluation. EPA/230/02-89-942.
USEPA, Office of Emergency and Remedial Response (Washington, DC). 1992. “Risk
Assessment Guidance for Superfund. Volume I: Human Health Evaluation Manual (Part A) –
Supplemental Guidance: Calculating the Concentration Term” OSWER Directive 9285.6-03;
Publication 9285.7-081; NTIS PB92-963373. May.
USEPA. 1992. Statistical Methods for Evaluating the Attainment of Cleanup Standards:
Volume III: Reference Based Standards for Soils and Media. EPA/230/R-94/004. December.
USEPA. 1996. Superfund Guidance for Evaluating the Attainment of Cleanup Standards.
Volume I. Soils and Solid Media. Center for Environmental Statistics. Available HTTP:
http://www.epa.gov.ces/pubs.htm.
C2 - 1
APPENDIX C-1: DETERMINATION OF THE APPLICABLE HUMAN HEALTH
STANDARD
Step 1. Determine Whether the De Minimis Standard is Appropriate for Your Site
The De Minimis Standard applies to chemicals for which the primary exposure routes
will be ingestion of soil or groundwater. For soil, the De Minimis Standard is either the risk-
based concentration (RBC) (Table 60-3b of the Rule and reproduced in Appendix C of this
Guidance) or the natural background levels of the contaminant, whichever is higher. Evaluating
a site based on the De Minimis Standard consists of aggregating site data and comparing either
maximum concentrations detected, or the 95% upper confidence limit of the arithmetic mean
(UCLM) concentration to established RBCs. If site concentrations do not exceed the RBC or
site-specific background, then no further evaluation or remediation of the site is required. The
De Minimis approach is limited to particular compounds (e.g., it does not apply to volatile
compounds), and is appropriate only for residential or industrial exposure scenarios. Below are
several questions that will help to determine whether your site may be evaluated under the De
Minimis Standard.
Check yes or no for each of the following questions:
1.1 Is more than one medium contaminated?
_ yes _ no
1.2 Are there more than 10 chemicals present at the site?
_ yes _ no
1.3 Are the chemicals at the site known to volatilize or to leach to groundwater?
_ yes _ no
1.4 Is future use of the site expected to be other than residential or industrial?
_ yes _ no
1.5 Does the site present attractive habitat for wildlife (e.g. wetlands)?
_ yes _ no
If all questions were answered with a “no”, the De Minimis approach is likely to be
appropriate for your site and the Worksheet C-1 should be completed. If there are any “yes”
responses to the questions above, the De Minimis standard may not be appropriate for the site
and more site-specific characterization is needed. If several or all questions were answered with
a “yes”, the De Minimis standard is probably not appropriate for your site and options under the
Uniform Standard or Site-Specific Assessment should be evaluated.
Step 2. Determine Whether the Uniform Standard is Appropriate for Your Site
C2 - 2
The Uniform Standard is based on the use of WVDEP approved methodologies to
calculate remediation standards. Equations and default input parameters are provided in
Appendix D. Advantages to using the Uniform Standard include the fact that this methodology
can be used to determine remediation standards for some chemicals not included under the De
Minimis Standard (e.g., volatile compounds), and that with adequate documentation, site-specific
information can be incorporated into the calculations. The disadvantages of the approach
defined under the Uniform Standard are that exposure scenarios and potential exposure pathways
included in these calculations are limited. Specifically, in order to evaluate a site based on the
Uniform Standard, land use must be either residential or industrial, and potential exposure
pathways for the site are limited to:
residential ingestion from drinking groundwater
residential ingestion from drinking surface water
residential inhalation of volatiles from groundwater
residential inhalation of volatiles from surface water
residential ingestion of soil
residential inhalation of volatiles and particulates from soil
industrial ingestion of soil
industrial inhalation of volatiles and particulates from soil
Below are several questions that will assist in determining whether application of the
Uniform Standard is appropriate for your site.
Check yes or no for each of the following questions:
2.1 Is future use of the site potentially other than residential or industrial use?
_ yes _ no
2.2 Is direct contact with impacted surface water (e.g., swimming or wading) likely to
occur at your site?
_ yes _ no
2.3 Do potentially impacted sediments exist at your site that you feel should not be
held to residential or industrial soil cleanup standards?
_ yes _ no
2.4 Do home vegetable gardens potentially exist in the vicinity of your site and is
homegrown produce potentially impacted by site-related chemicals?
_ yes _ no
C2 - 3
2.5 Is there any potential for human ingestion of fish that are impacted by site-related
chemicals?
_ yes _ no
2.6 Are there any dairy farms or livestock grazing areas within the area of impact of
your site?
_ yes _ no
2.7 Is impacted groundwater or surface water used for irrigation or any use other than
drinking water?
_ yes _ no
In addition, if you plan to use site specific modeling in determining exposure point
concentrations for media at your site, you should use the site specific assessment.
If you have answered “yes” to any of the questions 2.1 through 2.7 above, then there are
potential pathways for human exposure to site-related chemicals that are not addressed in the
methodology provided for determining a Uniform Standard. Therefore, a site-specific
assessment of human health risks may be more appropriate for your site.
Worksheet C-1. Compare Site Data to Chemical-Specific De Minimis RBC Values
Contaminant Max. Soil
Conc.
mg/kg
UCLM soil
mg/kg
Soil Ingestion RBCs
Residential/Industrial
mg/kg
Contaminant Max. GW
Conc.
ug/L
UCLM GW
ug/L
GW RBCs
ug/L
UCLM = 95% upper confidence limit on the arithmetic mean
RBC = Risk Based Concentrations provided in Table 60-3-b of the Rule
If the RBC value exceeds the UCLM site concentration value for a contaminant,
attainment is complete for that contaminant. If the UCLM concentrations for all site
contaminants are less than the corresponding RBC value, no remediation is required. If the site
values exceed the RBC values, additional assessment of the site is required. Refer to Figure 3-1
of this Guidance for a flow diagram regarding how to proceed.
C2 - 4
Table 60-3B
(currently under draft revision)
2/17/11
C2 - 5
APPENDIX C-2: CHECKLIST TO DETERMINE THE APPLICABLE ECOLOGICAL
STANDARD
This checklist is cross referenced to 60CSR3, the Voluntary Remediation and Redevelopment
Rule (the Rule). This checklist is based on Section 9.5 – Ecological – De Minimis Screening
Evaluation (cited as 60-3-9.5). The specific references are to subsections of this section of the
Rule.
Step 1. Determine Whether a De Minimis Ecological Screening Evaluation is Appropriate
for Your Site
See 60-3.9.5.a.1
Check “yes” or “no” to each of the following questions:
1.1 Has there been a release to the environment at or from the site?
___ yes ___ no ___ unknown
If the answer to 1.1 is “no”, then no further ecological evaluation is required. File
this completed form with the Final Report for the site. If the answer to 1.1 is “yes”
or “unknown”, proceed to Step 1.2.
1.2 Has the entire site been developed (e.g., predominantly covered by buildings,
pavement, etc.)?
___ yes ___ no
If “yes”, go to 1.6. If “no”, go to 1.3.
1.3 Are there any undeveloped areas on or adjacent to the site (e.g., areas that are not
under intensive landscape or agricultural control)?
___ yes ___ no
If the answer to 1.3 is “no” then no further ecological evaluation of terrestrial
habitat is required. Continue with Step 1.4.
1.4 Are there any potential wetlands (including vernal pools) on or adjacent to the site?
___ yes ___ no
If the answer to 1.4 is “no”, then no further ecological evaluation of wetland
habitats is required. Continue with Step 1.5.
C2 - 6
1.5 Are there any surface water bodies (i.e., lotic or lentic habitat) on or adjacent to the
site?
___ yes ___ no
If the answer to 1.5 is “no”, then no further ecological evaluation of lotic and lentic
aquatic habitat is required. Continue with Step. 1.6
1.6 Are there any terrestrial, wetland, or aquatic habitats off-site, but situated
downstream, downwind, or downgradient from the site that may be affected by site-
related stressors?
___ yes ___ no
1.7 Are there any project land uses for the site that would result in undeveloped areas,
wetland habitat, lotic habitat, or lentic habitat?
___ yes ___ no
If the answers to 1.3 through 1.7 are “no”, then no further ecological evaluation is
required. File this completed form with the Final Report of the site. If a question
was answered “yes”, then go to Step 2 because a complete exposure pathway may
exist for potential ecological receptors of concern.
Step 2. Identify any Readily Apparent Harm or Exceedances of Surface Water Quality
Standards.
See 60-3-2-2.44 and 60-3-9.5.a.5
2.1 Have there been any incidents where harm to wildlife attributable to contaminants
originating from the site has been readily apparent?
___ yes __ no
If the answer to 2.1 is “yes”, go to 2.2; if “no”, go to Step 2.3.
2.2 Has the cause of such harm been eliminated?
___ yes ___ no
If the answer to 2.2 is “yes”, briefly describe the action taken and continue with
this checklist.
C2 - 7
If “no”, the applicant can proceed directly to the remedy evaluation or alternately
proceed with a determination of a Uniform or Site Specific Ecological Standard, as
described in the guidance manual prior to implementation of the remedy.
2.3 Is the site contributing to exceedances of Surface Water Quality Standards established
for the protection of aquatic life (see 46 CSR1)?
___ yes ___ no
If the answer to 2.3 is “yes”, the applicant can proceed directly to the remedy
evaluation or, alternately, proceed with a determination of a Uniform or Site
Specific Ecological Standard, as described in the guidance manual prior to
implementation of the remedy.
If “no”, go to Step 3.
Step 3. Identification of Contamination Associated with Ecological Habitats
See 60-3-9.5.a.2 and 60-3-9.5.a.3
3.1 Have the environmental media (e.g., soil, surface water, sediment, biota) associated with
the ecological habitat(s) identified in 1.3 through 1.6 been sampled and analyzed with regard
to potential site-related contaminants of concern?
___ yes ___ no
If the answer to 3.1 is “yes”, proceed to 3.2; if “no”, proceed to Step 4.
3.2 Have any site-related contaminants been detected above natural background
concentrations in environmental media collected from terrestrial habitat?
___ yes ___ no ___ not applicable (no terrestrial)
3.3 Have any site-related contaminants been detected above natural background
concentrations in environmental media collected from wetland or aquatic habitats (lotic or
lentic habitats)?
___ yes ___ no ___not applicable (no wetland/aquatic habitat)
If the answer to 3.3 is “yes”, go to 3.4. If the answer is “no”, go to 3.6.
C2 - 8
3.4 Are site related contaminants presenting an ecological risk over and above “local”
condition?
___ yes ___ no
If the answer to 3.4 is “yes”, go to Step 4. If the answer is “no”, go to 3.5.
3.5 Have site-related releases of contaminants been stopped?
___ yes ___ no
If the answer to 3.5 is “yes”, go to 3.6. If the answer is “no”, go to Step 4.
3.6 Are site-related contaminants currently migrating to aquatic habitat (e.g., lotic, lentic,
or wetland habitat)?
___ yes ___ no ___ not applicable (no aquatic habitat)
If the answers to 3.2, 3.3, and 3.6 are “no” or “not applicable”, no further
ecological evaluation is required. File this completed form with the Final Report
for the site. If the answers to 3.2, 3.3, or 3.6 are “yes”, proceed to Step 4 because
a complete exposure pathway may exist.
Step 4. Characterize the Potential Ecological Habitat
See 60-3-9.5.a.4
4.1 Describe the general land use in the immediate vicinity of the site.
___ Urban ___ Industrial / Commercial
___ Rural / Agricultural ___ Rural / Undeveloped
___ Residential __ Other (Describe) ________________
4.2 For all affected areas that fulfill the descriptions in Questions 1.3 through 1.6, answer
the following and provide a site map identifying the potential ecological habitat.
4.2.1 Outline the following characteristics for potential terrestrial habitats.
Location: _____________________________________________________
Contiguous area: ________________________________________________
General topography: _____________________________________________
Predominant vegetation species: ________________________________ Primary soil type: ________________________________________________
C2 - 9
4.2.2 Outline the following characteristics for potential wetland habitats (e.g., vernal
pools, marshes, etc.
Location:__________________________________________________
Contiguous area: _____________________________________________
General topography: _____________________________________________
Predominant vegetation species: ______________________________ Primary soil type: _____________________________________________
4.2.3 Outline the following characteristics for potential lotic habitats (e.g., flowing water
habitat such as rivers and streams).
Location:__________________________________________________
Typical width and depth: _______________________________________
Typical flow rate: _____________________________________________
Typical gradient (m/km): _______________________________________
Type of river / creek bottom: ______________________________________
Types of aquatic vegetation present: _________________________________
Topography of the riparian zone: _________________________________
Predominant riparian vegetation: _________________________________
Human utilization of the river / creek and riparian zone: _______________
Local conditions: _____________________________________________
4.2.4 Outline the following characteristics for potential lentic habitats (e.g., standing water
habitats such as lakes and ponds).
Location:__________________________________________________
Is the pond / lake natural or man-made: ___________________________
Area of the pond / lake: _______________________________________
Typical and maximum depth: _______________________________________
Brief description of sources and drainage: ___________________________
Predominant aquatic vegetation: _________________________________
Topography of the littoral zone: _________________________________
Predominant vegetation in littoral zone: ___________________________
Human utilization of the pond / lake and shoreline: _____________________
Local conditions: _____________________________________________
4.3 Indicate if the site contains or is adjacent to any of the following types of valued
terrestrial habitats:
___ Area designated as a National Preserve
___ Federal land designated for protection of natural ecosystems
___ National or State wildlife refuge
___ Designated Federal wilderness area or administratively proposed wilderness area
___ Federal or State land designated for wildlife or game management
___ Nationa l or State park
___ National or State forest
___ State designated natural area
___ Climax community (e.g., old growth forest)
___ Area utilized for breeding by large or dense aggregations of wildlife
C2 - 10
___ Area important to the maintenance of unique biotic communities (e.g., area with a high proportion of endemic species
___ Critical habitat for federally designated threatened or endangered species
___ Habitat known to be used or potentially used by Federal or State designated
threatened or endangered species
___ Habitat needed for feeding, breeding, nesting, cover, or wintering habitat for
migratory birds
4.4 Indicate if the site contains or is adjacent to any of the following types of valued
wetlands: ___ Area important to the maintenance of unique biotic communities (e.g., area with a
high proportion of endemic species)
___ Area utilized for breeding by large or dense aggregations of wildlife
___ Feeding, breeding, nesting, cover, or wintering habitat for migratory waterfowl or
other aquatic birds
___ Spawning or nursery areas critical to the maintenance of fish / shellfish species
___ Critical habitat for Federal-designated threatened or endangered species
___ Habitat known to be used or potentially used by Federal or State designated thrthreatened or endangered species.
4.5 Indicate if the site is within or adjacent to any of the following valued aquatic habitats:
___ Area important to the maintenance of unique biotic communities (e.g., area with a
high proportion of endemic species
___ Critical areas identified under the Clean Lakes Program
___ National river reach designated as recreational
___ Federal or State designated scenic or wild river
___ Federal or State fish hatchery
___ Trout-stocked streams or wild trout streams with verified trout production
___ Habitat needed for feeding, breeding, nesting, cover, or wintering habitat for
migratory waterfowl or other aquatic birds
___ Spawning or nursery areas critical to the maintenance of fish / shellfish species
___ Critical habitat for Federal designated threatened or endangered species
___ Habitat known to be used or potentially used by Federal or State designated threatened or endangered species
4.6 Have valued terrestrial, wetland, or aquatic habitats been identified within or adjacent to
the site?
___ yes ___ no
(A list of agencies that can provide information that should assist in making a
determination of whether the site is located within or adjacent to the areas listed in
4.3, 4.4, and 4.5 is provided at end of Section C2)
After completing 4.6, proceed to Step 5.
C2 - 11
Step 5. Identify any Potential Ecological Receptors of Concern
See 60-3-2.2.14 and 60-3-9.5.a.4
5.1 Threatened and Endangered Species
Were any potential habitats within or adjacent to the site identified as critical
habitat for Federally designated threatened or endangered species listed in 50 CFS
17.95 or 17.96, or areas known to be used by Federal or State designated threatened
or endangered species?
___ yes ___ no
If “yes”, indicate which species:
Mammals: ___ Gray bat (Myotis grisescens)
___ Indiana bat (Myotis sodalis)
___ Virginia big-eared bat (Corynorhinus towsendii virginianus)
___ Virginia northern flying squirrel (Glaucomys sabrinus fuscus)
___ Eastern cougar (Felis concolor couguar)
Birds: ___ Bald eagle (Haliaeetus leucocephalus)
Amphibians: ___ Cheat Mountain salamander (Plethodon nettingi)
Snails:
___ Flat-spired three-toothed land snail (Triodopsis platysayoides)
Clams: ___ Pink mucket pearlymussel (Lampsilis abrupta)
___ Tuberculed blossom pearlymussel (Epioblasma torulosa torulosa)
___ James spinymussel (Pleurobema collina)
___ Fanshell (Cyprogenia stegaria)
___ Clubshell (Pleurobema clava)
___ Northern riffleshell (Epioblasma torulosa rangiana)
Flowering Plants:
___ Shale barren rock cress (Arabis perstellata)
___ Harperella (Ptilimnium nodosum)
___ Northeastern bulrush (Scirpus ancistrochaetus)
___ Virginia spiraea (Spiraea virginiana)
C2 - 12
___ Running buffalo clover (Trifolium stoloniferum)
___ Small whorled pogonia (Isotria medeoloides)
(The above list contains those federally designated threatened and endangered
species that are indigenous to West Virginia. They will be revised as necessary to
reflect changes to a species federal designation (e.g., addition or removal of a
species from the list of federally designated species). The West Virginia Division of
Natural Resources, Wildlife Resources Section should be consulted to ensure the
above list is current. Note that West Virginia has not established a list of State
designated threatened or endangered species. If such a list is established, the
Federal designated species list will be revised to include State designated
threatened and endangered species.)
5.2 Local populations that provide important natural or economic resources, functions,
and values
Were any valued terrestrial, wetland or aquatic habitats listed in 4.3, 4.4, or 4.5
identified within or adjacent to the site?
___ yes ___ no
(The valued terrestrial, wetland, and aquatic habitats listed in 4.3, 4.4, and 4.5 may
potentially contain local populations that provide important natural or economic
resources, functions, and values)
If 5.1 and 5.2 are answered “no” and surface water bodies are shown to be in
compliance with Appendix J. the ecological evaluation is complete and the site has
passed the De Minimis Ecological Screening Evaluation. File this completed form
with the Final Report for the site.
If either 5.1 or 5.2 are answered “yes”, the site does not pass the De Minimis
ecological risk screening since a complete exposure pathway may exist for
potential ecological receptors of concern. Further evaluation of the site is required
using either the Uniform Ecological Standard or the Site-specific Ecological
Standard. See Guidance Manual, Section 4.
C2 - 13
AGENCIES
West Virginia Division of Natural Resources
Main Office
State Capitol Complex, Building 3 1900
Kanawha Boulevard
Charleston, West Virginia 25305
(304) 558-2754 http://www.dnr.state.wv.us/default.htm
West Virginia Division of Natural Resources
Wildlife Resources Section
PO Box 67
Elkins, West Virginia 26241 (304) 637-0245
http://www.dnr.state.wv.us/wvwildlife/default.htm
West Virginia Division of Forestry
1900 Kanawha Boulevard East
Charleston, West Virginia 25303 (304) 558-2788
US Fish and Wildlife Service
West Virginia Ecological Services Field Office
Elkins Shopping Plaza
PO Box 1278
Elkins, West Virginia 26241
(304) 636-6586
http://northeast.fws.gov/wv.htm
US Department of Agriculture Natural
Resource and Conservation Service 75
Night Street --Room 301 Morgantown, WV
26505 (304) 291-4153
D - 1
APPENDIX D: EQUATIONS FOR THE UNIFORM HUMAN HEALTH STANDARDS
FOR SOIL AND DRINKING WATER
D.1 Introduction
As described in Section 3 of this guidance, if the De Minimis Human Health Standard is
not appropriate for a site or the applicant does not choose to evaluate the site under the De
Minimis Standard, then assessment can proceed under the Uniform Standard. Conducting a site
evaluation under the Uniform Standard may be appropriate if:
Concentrations of site-related chemicals exceed the De Minimis Human Health
Standards.
Chemicals present on the site are not appropriately evaluated under the De Minimis
Human Health Standard (e.g., the potential exists for volatilization or leaching to
groundwater).
If it is determined that the site is not appropriate for evaluation under the De Minimis
Human Health Standard, then the assessment with the next level of complexity is the Uniform
Human Health Risk-Based Standard7. This approach uses standard risk equations to arrive at
target concentrations for chemicals in soil, groundwater, and surface water at the site. This
appendix provides the equations and some default input parameters to calculate target soil and
water concentrations under the Uniform Human Health Risk-Based Standard. If concentrations
of chemicals at the site fall below the standards calculated using the equations presented in this
appendix, then it can be reasonably assumed that concentrations of chemicals at the site present
no unacceptable exposures to humans, and no further study is warranted. If the Uniform Risk-
Based Standards are exceeded by site concentrations, then further study or remediation is
warranted.
D.2 Exposure Pathways Considered in the Uniform Human Health Risk-Based
Standard
The equations and guidance for this section are excerpted from the United States
Environmental Protection Agency (USEPA) Region IX Preliminary Remediation Goals (USEPA
1996a) which are based on USEPA Risk Assessment Guidance for Superfund (RAGS: USEPA
1989) and the USEPA Soil Screening Guidance (USEPA 1996 b,c). These calculations consider
human exposure to contaminants of potential concern (COPCs) in soils, air, and water and assess
exposures that might occur under residential or industrial land use. Exposures from the several
potential exposure pathways are taken into account and are summarized in Table D-1.
7 It is not required that an applicant provide an assessment under the Uniform Standard if they do not meet the requirements of the De
Minimis Standard. It may be appropriate to conduct an assessment under the Site-Specific Standard rather than the Uniform Standard, as
depicted in Figure 3-1 of the Guidance.
D - 2
Table D-1: Typical Exposure Pathways by Medium for Residential and Industrial Land
Uses
Exposure Pathways Evaluated
Medium Residential Land Use Industrial Land Use
Ground Water Ingestion from drinking
Inhalation of volatiles
Surface Water Ingestion from drinking
Inhalation of volatiles
Soil Ingestion Ingestion
Inhalation of particulates Inhalation of particulates
Leaching to groundwater Leaching to groundwater
D.3 Input Parameters
Table D-2 provides a listing of the default input parameters for calculating residential or
industrial remediation standards. The default parameters provided are consistent with the
concept of evaluating a “Reasonable Maximum Exposure” (RME) and ensure that the calculated
standards are health protective. Default input parameters were obtained primarily from RAGS
Supplemental Guidance: Standard Default Exposure Factors, Office of Solid Waste and
Emergency Response (OSWER Directive 9285.6-03) (USEPA, 1991a) and more recent
information from USEPA’s Soil Screening Guidance (USEPA, 1996 2b,c), and the California
Environmental Protection Agency’s (Cal EPA) Preliminary Endangerment Assessment Guidance
Manual (Cal EPA 1994).
Table D-2: Standard Default Exposure Factors
Symbol Definition (units) Default Reference
CSFo Cancer slope factor oral (mg/kg-d)-1 Chemical-specific IRIS (USEPA 1998), HEAST (USEPA 1995)
CSFi Cancer slope factor inhaled (mg/kg-d)-1 Chemical-specific IRIS, (USEPA 1998), HEAST (USEPA 1995)
RfDo Reference dose oral (mg/kg-d) Chemical-specific IRIS, (USEPA 1998), HEAST (USEPA 1995)
RfCI Reference dose inhaled (mg/kg-d) Chemical-specific IRIS, (USEPA 1998), HEAST (USEPA 1995)
TRi Target cancer risk, industrial 10-5
WV VRR Rule (WVDEP, 1997)
TRr Target cancer risk, residential 10-6
WV VRR Rule (WVDEP, 1997)
THQ Target hazard quotient 1 WV VRR Rule (WVDEP, 1997)
BWa Body weight, adult (kg) 70 RAGS (Part A), USEPA 1989 (EPA/540/1-89/002)
BWc Body weight, child (kg) 15 Exposure Factors, USEPA 1991 (OSWER No.
9285.6-03)
ATc Averaging time-carcinogens (days) 25550 RAGS (Part A), USEPA 1989 (EPA/540/1-89/002)
ATn Averaging time-noncarcinogens (days) ED*365
IRAa Inhalation rate – adult (m3/day) 20 Exposure Factors, USEPA 1997
IRAc Inhalation rate – child (m3/day) 10 RAGS (Part A), USEPA 1989 (EPA/540/1-89/002)
IRWa Drinking Water ingestion – adult (L/day) 2 RAGS (Part A) USEPA 1989 (EPA/540/1-89/002)
D - 3
Symbol Definition (units) Default Reference
IRWc Drinking Water ingestion – child (L/day) 1 PEA, Cal-EPA (DTSC 1994)
IRSa Soil ingestion – adult (mg/day) 50 Exposure Factors, USEPA 1997 Exposure
Handbook
IRSc Soil ingestion – child (mg/day) 100 Exposure Factors, USEPA 1997 Exposure
Handbook (OWSER No. 9285.6-03), Soil
Screening
IRSo Soil ingestion – occupational (mg/day) 50 Exposure Factors, USEPA 1997 (OWSER No.
9285.6-03)
EFr Exposure frequency – residential (d/y) 350 Exposure Factors, USEPA 1997 (OWSER No.
9285.6-03)
EFo Exposure frequency – occupational (d/y) 250 Exposure Factors, USEPA 1997 (OWSER No.
9285.6-03)
EDr Exposure duration – residential (years) 30a Exposure Factors, USEPA 1997 (OWSER No.
9285.6-03)
EDc Exposure duration – child (years) 6 Exposure Factors, USEPA 1997 (OWSER No.
9285.6-03)
EDo Exposure duration – occupational (years) 25 Exposure Factors, USEPA 1997 (OWSER No.
9285.6-03)
Age-adjusted factors for carcinogens:
IFSadj Ingestion factor, soils ([mgyr]/[kgd]) 114 RAGS (Part B), USEPA 1997 (OSWER No.
9285.7-01B)
InhFadj Inhalation factor, soils ([m3yr]/[kgd]) 11 By analogy to RAGS (Part B)
IFWadj Ingestion factor, water ([lyr]/[kgd]) 1.1 By analogy to RAGS (Part B)
VFw Volatilization factor for water (L/m3) 0.5 RAGS (Part B), USEPA 1991 (OSWER No.
9285.7-01B)
PEF Particulate emission factor (m3/kg) See Section D, 4.3 Soil Screening Guidance (USEPA 1996a,b)
VFs Volatilization factor for soil (m3/kg)) See below D, 4.3 Soil Screening Guidance (USEPA 1996a,b)
Sat Soil saturation concentration (mg/kg) See below D, 4.4 Soil Screening Guidance (USEPA 1996a,b)
Footnote:
a
Exposure duration for lifetime residents is assumed to be 30 years total. For
carcinogens, exposures are combined for children (6 years) and adults (24 years).
b IRIS = Integrated Risk Information System (USEPA 1998)
c HEAST = Health Effects Assessment Summary Tables (USEPA 1995)
WV VRR Rule = West Virginia Voluntary Remediation and Redevelopment Rule
(WVDEP 1997)
Because contact rates may be different for children and adults, carcinogenic risks during
the first 30 years of life were calculated using age-adjusted factors (“adj”). Use of age-adjusted
factors are especially important for soil ingestion exposures, which are higher during childhood
and decrease with age. However, for purposes of combining exposures across pathways,
additional age-adjusted factors are used for inhalation. These factors approximate the integrated
exposure from birth until age 30 combining contact rates, body weights, and exposure durations
or two age groups – small children and adults. Age-adjusted factors were obtained from RAGS
Part B (USEPA 1991b) or developed by analogy as described below.
D - 4
For soils only, non carcinogenic contaminants are evaluated in children separately from
adults. No age-adjustment factor is used in this case. The focus on children is considered
protective of the higher daily intake rates of soil by children and their lower body weight. For
maintaining consistency when evaluating soils, inhalation exposures are also based on childhood
contact rates.
(1) ingestion ([mgyr]/[kgd]):
a
AcR
C
Cc
adjBW
IRSxEDED
BW
IRSxEDIFS
(2) inhalation ([m3yr]/[kgd]):
a
AcR
C
Cc
adjBW
IRAxEDED
BW
IRAxEDInhF
If site-specific information suggests that the default input parameters provided are not
appropriate for a site, then the site-specific inputs can be incorporated into equations. Site-
specific information may be available for a variety of parameters. Types of information that may
be appropriate to incorporate into a site assessment include (but are not limited to):
Data on soil parameters from site characterization efforts, such as total organic
carbon, soil density, or soil porosity
Human activity information from land use assessments, such as exposure
frequency, inhalation rates, exposure duration, or contact rates
Miscellaneous information from interviews with individuals living in the area or
involved with land use scenarios similar to those envisioned for the site.
D.4 Uniform Risk-Based Equations
The equations used to calculate remediation standards for carcinogenic and
noncarcinogenic contaminants are presented in Equations D-1 through D-8. The equations
update RAGS Part B equations. This methodology backcalculates a soil, air, or water
concentration level from a target risk (for carcinogens) or hazard quotient (for noncarcinogens).
For completeness, the soil equations combine risks from ingestion, and inhalation
simultaneously.
D.4.1 Soil Equations
For soils, equations were based on two exposure routes (ingestion and inhalation).
+
D - 5
Equation D-1: Combined Exposures to Carcinogenic Contaminants in Residential Soil
C mg kgTR x AT
EFIFS x CSF
mg kg
InhF x CSF
VF or PEF
c
r
adj o adj i
s
/
/
106
Equation D-2: Combined Exposures to Noncarcinogenic Contaminants in Residential Soil.
PEForVF
IRAx
RfDikgmg
IRSx
RfDEDcxEF
ATxBWxTHQkgmgC
s
cc
r
nc
1
/610
1
/
0
Equation D-3: Combined Exposures to Carcinogenic Contaminants in Industrial Soil
C mg kgTR x BW x AT
EF x EDIRS x CSF
mg kg
IRA xCSF
VF or PEF
a
O
c
o
o o a i
s
/
/
106
Equation D-4: Combined Exposures to Noncarcinogenic Contaminants in Industrial Soil
C mg kgTHQ x BW x AT
EF x EDRfD
xIRS
mg kg RfDx
IRA
VF or PEF
a n
o
i
a
s
O
o
o
/
/
1
10
16
Calculation of the volatilization factor for soil (VFs) is presented in Subsection D.4.3.1.
Calculation of the particulate emission factor (PEF) is presented in Subsection D.4.3.2. Use VF
for volatile chemicals (i.e., having a Henry’s Law Constant greater than 10-5
and a molecular
weight less than 200 grams/mole [gm/mole] or a PEF for non-volatile chemicals. The equation
used to calculate the remediation standard should include risk due to fugitive dust and risk due to
volatilization from soil, if both apply.
D.4.2 Tap Water Equations
For tap water, an upperbound volatilization constant (VFw) may be used that is based on
all uses of household water (e.g., showering, laundering, and dish washing). Certain assumptions
were made in deriving this constant. For example, it was assumed that the volume of water used
in a residence for a family of four is 720 liters per day (L/day), the volume of the dwelling is
150,000 L and the air exchange rate is 0.25 air changes/hour (RAGS Part B: USEPA 1991b).
Furthermore, it was assumed that the average transfer efficiency weighted by water use is 50
D - 6
percent (i.e. half of the concentration of each chemical in water will be transferred into air by all
water uses). Note: the range of transfer efficiencies extends from 30 percent for toilets to 90
percent for dishwashers. If site-specific information is available, it may be used to develop a
site-specific VFw.
Equation D-5: Ingestion and Inhalation Exposures to Carcinogenic Contaminants in Water
Equation D-6: Ingestion and Inhalation Exposures to Noncarcinogenic Contaminants in Water
D.4.3 Air Equations for Emissions from Soils
USEPA toxicity criteria indicate that risks from exposure to some chemicals in soil via
inhalation after release to air may far outweigh the risk via ingestion of the soil; therefore, as
presented previously in equations D-1 through D-4, calculations under the Uniform Standard
have been designed to address this pathway as well The models used to calculate standards for
inhalation of volatiles/particulates are updates of risk assessment methods presented in RAGS
Part B (USEPA 1991b) and are consistent with the Soil Screening Guidance: User’s Guide and
Technical Background Document (USEPA 1996a,b).
To address the soil-to-air pathways the calculations incorporate volatilization factors
(VFs) for volatile contaminants and particulate emission factors (PEF) for nonvolatile
contaminants. These factors relate soil contaminant concentrations to air contaminant
concentrations that may be inhaled on-site. The VFs and PEF equations can be broken into two
separate models; an emission model to estimate emissions of the contaminant from the soil and a
dispersion model to simulate the dispersion of the contaminant in the atmosphere.
It should be noted that the box model in RAGS Part B has been replaced with a
dispersion term (Q/C) derived from a modeling exercise using meteorological data from 29
locations across the United States because the box model may not be applicable to a broad range
of site types and meteorology and does not utilize state-of-the-art techniques developed for
regulatory dispersion modeling. The dispersion model for both volatiles and particulates is the
AREA-ST, an updated version of the Office of Air Quality Planning and Standards, Industrial
Source Complex Model (ISC2). However, different Q/C terms are used in the VF and PEF
equations. Los Angeles was selected as the 90th
percentile data set for volatiles and Minneapolis
was selected as the 90th
percentile data set for fugitive dusts (USEPA 1996b,c). A default source
size of 0.5 acres was chosen for the calculations. If unusual site conditions exists such that the
area source is substantially larger than the default source size assumed here, an alternative Q/C
could be applied (see USEPA 1996b,c).
C g LTR AT g mg
EF IFW CSF VF InhF CSF
c
r adj o w adj i
( / )/
[( ) ( )]
1000
C g LTHQ BW AT g mg
EF EDIRW
RfD
VF IRA
RfD
a n
r ra
o
w a
i
( / )/
[( ) ( )]
1000
D - 7
D.4.3.1 Soil-to-Air Volatilization Factor
Volatile chemicals, defined as those chemicals having a Henry's Law constant greater
than 10-5
(atm-m3/mol) and a molecular weight less than 200 g/mole, should be screened for
inhalation exposures using a VFS. To calculate remediation standards for volatile chemicals in
soil, a chemical-specific volatilization factor is calculated per Equation D-7. Because of its
reliance on Henry's law, the VFS model is applicable only when the contaminant concentration in
soil is at or below saturation (i.e. there is no free-phase contaminant present).
The emission terms used in the VFs are chemical-specific and may be calculated from
physical-chemical information obtained from a number of sources including Superfund Exposure
Assessment Manual (USEPA 1988), Subsurface Contamination Reference Guide (USEPA
1990a), Fate and Exposure Data (Howard 1989-1993), and Superfund Chemical Data Matrix
(US EPA 1994c). In those cases where Diffusivity Coefficients (Di) are not provided in existing
literature, Di's may be calculated using Fuller's Method described in USEPA (1988). A surrogate
term may be used for some chemicals that lack physio-chemical information. In those cases, a
proxy chemical of similar structure may be used that may over- or under-estimate the cleanup
standard for soils.
Equation D-7 forms the basis for deriving uniform soil remediation standards for the
inhalation of volatiles pathway. The following parameters in the standardized equation can be
replaced with site-specific data.
Source area
Average soil moisture content
Average fraction organic carbon content
Dry soil bulk density.
The basic principle of the VFs model is applicable only if the soil contaminant
concentration is at or below soil saturation (“sat”, see section D.4.4). Above this level, the
model cannot predict an accurate VFs. If the Cleanup Standard calculated using VFs is greater
than the calculated “sat” (Equation D-9), the remediation standard should be set equal to “sat” in
accordance with Soil Screening Guidance (USEPA 1996 b,c).
D - 8
Equation D-7: Derivation of the Volatilization Factor
where:
Parameter Definition (units) Default
VFs Volatilization factor (m3/kg) --
DA Apparent Diffusivity (cm2/s) --
Q/C Inverse of the mean conc. At
the center of a 0.5-acre
square source (g/m2-s per
kg/m3)
68.81
T Exposure interval (s) 9.5108
b Dry soil bulk density (g/cm3) 1.5
a Air filled soil porosity
(Lair/Lsoil) 0.28 or n-w
n Total soil porosity
(Lpore/Lsoil) 0.43 or 1 – (b/s)
W Water-filled soil porosity
(Lwater/Lsoil)
0.15
s Soil particle density (g/cm3) 2.65
Di Diffusivity in air (cm2/s) Chemical-specific
H’ Dimensionless Henry’s Law
constant
Calculated from H by
multiplying by 41 (U.S.
EPA 1991a)
H Henry’s Law Constant (atm-
m3/mol)
Chemical-specific
Dw Diffusivity in water (cm2/s) Chemical-specific
Kd Soil-water partition
coefficient (cm3/g) = Kocfoc
Chemical-specific
Koc Soil organic carbon-water
partition coefficient (cm3/g)
Chemical-specific
foc Fraction organic carbon in
soil (g/g)
0.006 (0.6%)
VF m kg Q CD T
Dm cm
sA
b A
( / ) ( / )( . )
)( / )
/ /23
14 2 2314
210
DD H D n
K HA
a i w w
b d w a
[( ) / ]/ ' /
'
10 3 10 3 2
D - 9
D.4.3.2 Soil-to-Air Particulate Emission Factor (PEF)
Inhalation of chemicals adsorbed to respirable particles (PM10) were assessed using a
default PEF equal to 1. 316109 cubic meters per kilogram (m
3/kg) that relates the contaminant
concentration in soil with the concentration of respirable particles in the air due to fugitive dust
emissions from contaminated soils. The generic PEF was derived using default values in
Equation D-8, which corresponds to a receptor point concentration of approximately 0.76
micrograms per cubic meter ( µg/m3)
. The relationship is derived by Cowherd (1985) for a rapid
assessment procedure applicable to a typical hazardous waste site where the surface
contamination provides a relatively continuous and constant potential for emission over an
extended period of time (e.g., years). This represents an annual average emission rate based on
wind erosion that should be compared with chronic health criteria; it is not appropriate for
evaluating the potential for more acute exposures.
With the exception of specific heavy metals, the PEF does not appear to significantly
affect most soil standards. Equation D-8 forms the basis for deriving a generic PEF for the
inhalation of particulates pathway. For more details regarding specific parameters used in the
PEF model, the reader is referred to Soil Screening Guidance: Technical Background Document
(USEPA 1996b).
Note: The generic PEF evaluates windborne emissions and does not consider dust
emissions from traffic or other forms of mechanical disturbance that could lead to greater
emissions than assumed here.
Equation D-8: Derivation of the Particulate Emission Factor
Parameter Definition (units) Default
PEF Particulate emission factor (m3/kg) 1.316 10
9
Q/C Inverse of the mean concentration at
the center of a 0.5-acre-square source
(g/m2-s per kg/m
3)
90.80
V Fraction of vegetative cover (unitless) 0.5
Um Mean annual windspeed (m/s) 4.69
Ut Equivalent threshold value of
windspeed at 7 m (m/s)
11.32
F(x) Function dependent on Um/Ut derived
using Cowherd (1985) (unitless)
0.194
PEF m kg Q Cs h
V U U F xm t
( / ) //
. ( ) ( / ) ( )
3
3
3600
0 036 1
D - 10
D.4.4 Soil Saturation Concentration
Soil saturation ("sat") corresponds to the contaminant concentration in soil at which the
adsorptive limits of the soil particles and the solubility limits of the available soil moisture have
been reached. Above this point, pure liquid-phase contaminant is expected in the soil. If the
Standard calculated using VFs is greater than the calculated sat, the Standard should be set equal
to sat, in accordance with Soil Screening Guidance (USEPA 1996 b,c). The updated equation for
deriving sat is presented in Equation D-9.
Equation D-9: Derivation of the Soil Saturation Limit
Parameter Definition (units) Default
Sat Soil saturation concentration (mg/kg) --
S Solubility in water (mg/L-water) Chemical-specific
b Dry soil bulk density (kg/L) 1.5
Kd Soil-water partition coefficient (L/kg) Koc foc
(chemical-
specific)
Koc Soil organic carbon/water partition
coefficient (L/kg)
Chemical-specific
foc Fraction organic carbon in soil (g/g) 0.006 (0.6%)
W Water-filled soil porosity (Lwater/Lsoil) 0.15
a Air filled soil porosity (Lair/Lsoil) 0.28 or no-w
H Henry’s Law constant (atm-m3/mol) Chemical-specific
H' Dimensionless Henry’s Law constant H 41, where 41
is a units
conversion factor
D.4.5 Migration to Groundwater Pathway
The methodology for calculating a soil standard for the migration to groundwater was
developed to identify chemical concentrations in soil that have the potential to contaminate
groundwater. Migration of contaminants from soil to groundwater can be envisioned as a two-
stage process: (1) release of contaminant in soil leachate and (2) transport of the contaminant
through the underlying soil and aquifer to a receptor well. The methodology considers both of
these fate and transport mechanisms, and is based on the methodology presented in USEPA’s
Soil Screening Guidance: Users Guide (USEPA 1996c).
satS
K Hb
d b w a
( )'
D - 11
To calculate a remediation standard for soil that will protect for the migration to
groundwater pathway, multiply the acceptable groundwater concentration by the dilution factor
to obtain a target soil leachate concentration. A default value of 20 can be used for the dilution
factor, or site information can be used to calculate a value using Equation D-10. For example, if
the dilution factor is 20 and the acceptable ground water concentration is 0.05 mg/L, the target
soil/water leachate concentration would be 1.0 mg/L. Next, the partition equation (Equation
D-11) is used to calculate the total soil concentration corresponding to this soil leachate
concentration. Alternatively, if a site-specific leach test is used, compare the target soil leachate
concentration to extract concentrations from the leach tests. For further information regarding
the calculations of standards based on leaching from soil to groundwater, the reader is referred to
USEPA Soil Screening Guidance: User’s Guide (USEPA 1996c).
Equation D-10: Derivation of Dilution Factor
Parameter/Definition (units) Default
Dilution factor (unitless) 20 (0.5-acre source)*
K/aquifer hydraulic conductivity (m/yr) Site-Specific
i/hydraulic gradient (m/m) Site-Specific
I/infiltration rate (m/yr) Site-Specific
d/mixing zone depth (m) Site-Specific
L/source length parallel to groundwater flow (m) Site-Specific
*Use default dilution factor of 20 or calculate a value based on site-specific parameters.
Equation D-11: Soil Screening Level Partitioning Equation for Migration to Groundwater
Screening Level in Soil mg kg C KH
w d
w a
b
( / ) [( )
]'
IL
Kidfactordilution 1
D - 12
Parameter/Definition (units) Default
Cw/target soil leachate concentration
(mg/L)
Nonzero MCLG, MCL, or health-based
level dilution factor
Kd.soil/water partition coefficient (L/kg) Chemical-specific
Koc/soil organic carbon/water partition
coefficient (L/kg) Kocfoc (organics) chemical-specific
Foc/fraction organic carbon in soil (g/g) 0.002 (0.2%)
w/water-filled soil porosity (Lwater/Lsoil) 0.3
a/air-filled soil porosity (Lair/Lsoil) n - w
b/dry soil bulk density (kg/L) 1.5
n/soil porosity (Lpore/Lsoil) 1-(b/s)
s/soil particle density (kg/L) 2.65
H'/dimensionless Henry’s law constant Chemical-specific (assume to be zero
for inorganic contaminants except
mercury)
The USEPA methodology was designed for use during the early stages of a site
evaluation when information about subsurface conditions may be limited. Because of this
constraint, the methodology is based on conservative, simplifying assumptions about the release
and transport of contaminants in the subsurface.
D.5 References
California Environmental Protection Agency (Cal EPA). 1994. Preliminary
Endangerment Assessment Guidance Manual. Department of Toxic Substances
Control, Sacramento, California.
Cowherd, C., G. Muleski, P. Engelhart, and D. Gillette. 1985. Rapid Assessment
of Exposure to Particulate Emission from Surface Contamination. EPA/600/8-
85/002. Prepared for Office of Health and Environmental Assessment, U.S.
Environmental Protection Agency, Washington, DC. NTIS PB85-192219 7AS.
Howard, P.H. 1989-1993. Handbook of Environmental Fate and Exposure Data
for Organic Chemicals. Lewis Publishers, Chelsea, Michigan.
United States Environmental Protection Agency (USEPA). 1988. Superfund
Exposure Assessment Manual. EPA/540/1-88/001. Office of Emergency and
Remedial Response, Washington, DC.
United States Environmental Protection Agency (USEPA). 1989. Risk
Assessment Guidance for Superfund: Volume I- Human Health Evaluation
D - 13
Manual (Part A). Office of Emergency and Remedial Response. EPA/540/1-
89/002.
United States Environmental Protection Agency (USEPA). 1990a. Subsurface
Contamination Reference Guide. EPA/540/2-90/011. Office of Emergency and
Remedial Response, Washington, DC.
United States Environmental Protection Agency (USEPA). 1991a. Human
Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure
Factors. Publication 9285.6-03. Office of Emergency and Remedial Response,
Washington, DC. NTIS PB91-921314.
United States Environmental Protection Agency (USEPA). 1991b. Risk
Assessment Guidance for Superfund Volume 1: Human Health Evaluation
Manual (Part B, Development of Risk-Based Preliminary Remediation Goals).
Publication 9285.7-01B. Office of Emergency and Remedial Response,
Washington, DC. NTIS PB92-963333.
United States Environmental Protection Agency (USEPA). 1994. Superfund
Chemical Data Matrix. EPA/540/R-94/009. Office of Solid Waste and
Emergency Response, Washington, DC. PB94-963506.
United States Environmental Protection Agency (USEPA). 1995. Health Effects
Assessment Summary Tables (HEAST): Annual Update, FY 1994.
Environmental Criteria Assessment Office, Office of Health and Environmental
Assessment, Office of Research and Development, Cincinnati, OH.
United States Environmental Protection Agency (USEPA). 1996a. Region 9
Preliminary Remediation Goals. San Francisco, CA. Stanford J. Smucker,
Regional Toxicologist.
United States Environmental Protection Agency (USEPA). 1996b. Soil
Screening Guidance: Technical Background Document. EPA/540/R-95/128.
Office of Emergency and Remedial Response, Washington, DC. PB96-963502.
United States Environmental Protection Agency (USEPA). 1996c. Soil
Screening Guidance: User's Guide. EPA/540/R-96/018. Office of Emergency
and Remedial Response, Washington, DC. PB96-963505.
United States Environmental Protection Agency (USEPA). 1998. Integrated
Risk Information System (IRIS). (www.epa.gov/ngispgm3/iris).
West Virginia Division of Environmental Protection (WVDEP). 1997. Title 60
Legislative Rule. Bureau of Environment. Division of Environmental Protection.
Director’s Office. Series 3 Voluntary Remediation and Redevelopment Rule.
July.
United States Environmental Protection Agency (USEPA). 1997. Exposure
Factors Handbook.
E - 1
APPENDIX E: RELATIVE ABSORPTION FACTORS AND BIOAVAILABILITY
E.l Introduction
This appendix provides an overview of relative absorption factors and bioavailability
adjustments, the methods for measuring them, and their use in risk assessments. The two
primary issues addressed are adjustment of oral toxicity values used in assessing dermal
exposures, and adjustment of dermal and oral intake values to account for variations in
absorption from different media. Further guidance on adjustments for absorption efficiency,
including adjustments of toxicity values from administered to absorbed dose, can be found in the
United States Environmental Protection Agency (USEPA) Risk Assessment Guidance for
Superfund, Appendix A (USEPA, 1989). Terms used are defined at the end of this section.
Absorption adjustments are used in the risk characterization step to ensure that the site
exposure estimate and the toxicity value for comparison are both expressed as absorbed doses, or
that both are expressed as intake values. Adjustments may be necessary to match the exposure
estimate with the toxicity value, if one is based on an absorbed dose and the other is based on an
intake (i.e., administered dose). For the dermal route of exposure, toxicity values that are
expressed as administered dose will need to be adjusted to absorbed doses for comparison. This
adjustment is discussed below.
Adjustments also may be necessary to account for the different absorption efficiencies
associated with different exposure media (e.g., contaminants ingested with food or soil may be
less completely absorbed than contaminants ingested with water). If the medium of oral
exposure in the site exposure assessment differs from the medium of exposure assumed by the
toxicity value, an absorption adjustment may be appropriate to express the site exposure in terms
that are comparable to the toxicity value. This adjustment is termed a relative absorption factor
(RAF). For example, a substance might be more completely absorbed following exposure to the
substance in drinking water than following exposure to food or soil containing the substance. A
relative absorption factor would then be used to adjust the food or soil ingestion exposure
estimate to match a reference dose (RfD) or cancer slope factor (CSF) based on an assumption of
drinking water ingestion. This adjustment is discussed below.
E.2 Definitions
Absorbed dose. The amount of a substance that penetrates the exchange
boundaries of an organism after contact. Absorbed dose is calculated from the
intake and the absorption efficiency, and is usually expressed as mass of a
substance absorbed into the body per unit body weight per unit time (e.g., mg/kg-
day).
Administered dose. The mass of substance administered to an organism and in
contact with an exchange boundary (e.g., gastrointestinal tract) per unit body
weight per unit time (e.g., mg/kg-day).
Bioavailability. The bioavailability of a substance may be defined in a variety of
ways, depending upon the interests of the investigator and the specific objectives
E - 2
of a given study. For the purpose of this guidance, bioavailability is defined as
the fraction of an administered dose that reaches the central (blood) compartment.
Bioavailability defined in this manner is commonly referred to as “absolute
bioavailability”.
Cancer Slope Factor. A plausible upper-bound estimate of the probability of a
response per unit intake of a chemical over a lifetime. The CSF is used to
estimate an upper-bound probability of an individual developing cancer as a result
of a lifetime of exposure to a particular level of a potential carcinogen.
Exposure Route. The way a chemical or physical agent comes in contact with an
organism (i.e., by ingestion, inhalation, or dermal contact).
Exposure Medium. The various materials to which an organism may be exposed
(e.g., water, food, or soil).
Intake. A measure of exposure expressed as the mass of substance in contact with
the exchange boundary per unit body weight per unit time (e.g., mg/kg-day).
Also termed the normalized exposure rate, and equivalent to administered dose.
Reference Dose. The USEPA’s preferred toxicity value for evaluating
noncarcinogenic effects resulting from exposures to toxic substances.
Relative Absorption Factor. The RAF describes the absorbed fraction of a
contaminant from a particular exposure medium relative to the fraction absorbed
from the dosing vehicle used in the toxicity study for that compound.
Relative Bioavailability. Relative bioavailability refers to comparative
bioavailabilities from different exposure media (e.g., bioavailability from soil
relative to bioavailability from water), expressed in this guidance as a fractional
relative absorption factor (RAF).
E.3 Bioavailability Adjustments for Assessing Dermal Exposures
E.3.1 Converting Oral Toxicity Values from Administered to Absorbed Doses
Because there are few, if any, toxicity values for dermal exposure, oral toxicity values
will need to be used to assess risks from dermal exposure. The following guidance is based on
Appendix A of USEPA’s Risk Assessment Guidance for Superfund (USEPA, 1989). Most oral
toxicity values (i.e., RfDs and CSFs) are expressed as the amount of substance administered per
unit time and unit body weight, whereas exposure estimates for the dermal route of exposure are
eventually expressed as absorbed doses. Thus, for dermal exposure to contaminants in water or
in soil, it may be necessary to adjust an oral toxicity value from an administered to an absorbed
dose. An oral RfD may be converted to absorbed dose by multiplying the RfD by the fractional
absorption value (ABS); i.e.,
RfDO ABS = RfDABS
E - 3
An oral cancer slope factor may be converted to absorbed dose by dividing the cancer
slope factor by the fractional absorption value, i.e.,
CSFO/ABS = CSFABS.
Adjustments for an oral RfD and an oral slope factor, respectively, are shown in
Examples E-1 and E-2.
If the oral toxicity value is already expressed as an absorbed dose (e.g, trichloroethylene),
it is not necessary to adjust the toxicity value.
USEPA’s Integrated Risk Information System (IRIS) files and Agency for Toxic
Substances Disease Registry (ATSDR) toxicity profiles are good sources of oral absorption
estimates. Hrudley et al (1996) also provides an extensive review of oral absorption estimates
for a number of compounds. Because oral absorption may vary with the matrix administered
(e.g., water vs. diet), the absorption values used should be appropriate for the matrix
administered in the toxicity studies that serve as the basis for the oral toxicity values.
In the absence of any information on absorption for the substance or chemically related
substances, one must assume an oral absorption efficiency. Assuming 100 percent absorption in
an oral administration study that serves as the basis for an RfD or slope factor would be a very
conservative approach for estimating the dermal RfD or slope factor (i.e., depending on the type
of chemical, the true absorbed dose might have been much lower than 100 percent; hence, an
absorbed-dose RfD should similarly be much lower, or the slope factor should be much higher).
For example, some metals tend to be poorly absorbed (less than 5 percent) by the gastrointestinal
tract. A relatively conservative assumption for oral absorption in the absence of appropriate
information would be 5 percent.
E.3.2 Dermal Absorption Estimates for Sediment and Soil Contact
The adjusted toxicity values reflecting absorbed dose may be used to assess dermal
exposure to chemicals in water, sediments, or soil. The National Center for Exposure
Assessment (www.epa.gov.ncea/index.html) may be a source of oral absorption estimates for
oral to dermal adjustments of toxicity values. When assessing dermal exposures to chemicals in
sediments or soil, it is also necessary to estimate dermal absorption. USEPA Region III has
provided guidance, with default assumptions, for a number of chemicals (USEPA, 1995). These
values are listed below. The guidance is available via the internet at
http://www.epa.gov/reg3hwand/risk/solo.bsg2.htm. Additional information is available by
calling (215) 597-1309.
E - 4
Chemicals (s) Default Dermal Absorption (%)
Arsenic 3
Cadmium 1
Other metals 1
Volatile organic compounds (vapor pressure
95.2 mm Hg), e.g., benzene, 1,1-DCE,
1,1,1-TCE)
0.05
(vapor pressure <95.2, e.g., ethylbenzene,
PCB, toluene, xylenes)
3
Chlorinated dioxins 3
Pentachlorophenol 24.4
Pesticides 10
PCBs 6
Other semivolatile compounds 10
Although these serve as default values, applicants may wish to consult recent literature,
or to conduct studies of their own. USEPA has provided comprehensive guidance regarding the
assessment of dermal absorption (USEPA 1992), and has several research projects underway.
E.4 Relative Absorption Factors for Assessing Oral Exposures
E.4.1 Adjustment for Medium of Exposure
As discussed above, if the medium of oral exposure in the site exposure assessment
differs from the medium of exposure assumed in the oral toxicity assessment, then an accurate
assessment of site risks may require an absorption adjustment to express the exposures in the
same terms. Such adjustments may be applied in assessing oral exposures to metals, pesticides,
and other semivolatile organic compounds. Generally, bioavailability is expected to decrease as
volatility decreases, and soil residence times increase. Frequently, toxicity values are based on
have been adjusted to reflect exposures to chemicals in drinking water or diet, while the site
exposure of concern is to chemicals in soil. Because the absorption of chemicals in soil is often
less than their absorption from drinking water, a comparison of relative absorption efficiencies is
necessary to adjust the site exposure to that on which the RfD or slope factor is based. In some
cases, the absorption of a chemical from the dosing medium and the absorption from soil are
both known, and an RAF can be calculated by dividing the absorption from soil by the
absorption from the dosing medium. This RAF is used to adjust the chronic daily intake (CDI)
value; i.e.,
CDI x RAF = adjusted CDI.
An example calculation to adjust for medium of exposure is given in Example E-3.
In most cases, an RAF will be determined experimentally without specifically identifying
absorption from the dosing medium. Methods for conducting such studies are described below.
Table E-1 presents default values that may be applied for some chemicals in soil.
E - 5
E.4.2 Methods of Assessing Bioavailability
Several methods are available for estimating the extent of oral absorption of compounds
from environmental matrices. The method selected for a specific study will depend on the
characteristics of the compound being studied and on the end use of the resulting data. Data
requirements for an accurate assessment of relative bioavailability (i.e., absorption from an
environmental matrix relative to absorption from the dose formulation used in the toxicity study)
are substantially less rigorous than those for an accurate determination of absolute
bioavailability. For this reason, and because measures of relative bioavailability are generally
most useful for risk assessment, most studies are designed to determine relative bioavailability.
Relative bioavailability may be determined by comparing tissue concentrations after doses are
administered, or by comparing the likely extent of dissolution of different formulations in the
gastrointestinal tract. Such comparisons of extent of dissolution may be conducted using in vitro
test systems that mimic gastrointestinal tract processes. Both in vivo and in vitro methods of
assessing oral bioavailability are reviewed below.
E.4.2.1 In Vivo Methods of Assessing Bioavailability
Animal models have been developed for evaluating the relative bioavailability of arsenic
(swine and monkeys), cadmium (weanling rats), mercury, lead (weanling rats and weanling
swine), polycyclic aromatic hydrocarbons (PAHs; mice), polychlorinated biphenyls (PCBs, rats)
petroleum hydrocarbons (mice), and tetrachlorodibenzo-p-dioxin (TCDD; rats). The reader is
referred to the references in Table E-2 for further information on the design and application of
these animal models.
E.4.2.2 In Vitro Methods of Assessing Bioavailability
Physiologically based in vitro models have been developed for assessing relative lead
bioavailability from soil and have been validated against results from in vivo studies in weanling
rats (Ruby et al 1996) and weanling swine (Medlin 1997). The in vitro method presented in
Medlin (1997) is recommended for assessing relative lead bioavailability from soil.
A physiologically available cyanide in vitro method has been developed by Magee et al.
(1996a) in conjunction with the Massachusetts Department of Environmental Protection. This
method is appropriate for evaluating the bioavailability of complexed cyanide from soil.
Additional in vitro methods for assessment of arsenic, cadmium, chromium, mercury, and
PAH bioavailability are under development. As these methods are validated, they may also
become acceptable for use in human health risk assessment.
E.4.3 Other Methods of Assessing Bioavailability
Less precise information about relative bioavailability can also be obtained using less
rigorous methods, i.e., the methods described below yield qualitative information that is not
appropriate for use in quantitative adjustments to risk assessments. Standard leaching tests, such
as the Toxicity Characteristics Leaching Procedure (TCLP) or the Synthetic Precipitation
E - 6
Leaching Procedure (SPLP) indicate whether a chemical will have limited potential to dissolve
in the gastrointestinal tract. Limited ability to leach a chemical from soil may also indicate a
limited ability to remove the chemical from soil during remediation.
For metals, mineralogical studies may be used to identify the specific metal compounds
present in soil. If the bioavailability of the individual metal compounds – relative to the
compound tested in toxicity studies relied upon by USEPA – is known, it may be possible to
predict the relative bioavailability of the metal in soil. Such predictions are not likely to be as
accurate as directly testing the soil, however, due to interactions of metal ions with soil
constituents. Such interactions are likely to further modify the solubility and bioavailability of
the metal in soil.
E.4.4 Guidance for Selecting Study Methods
This brief summary of methods for assessing oral bioavailability provides a hierarchy for
evaluating bioavailability data. Animal studies are generally considered the most reliable, but
are also more expensive and time consuming than in vitro studies. Protocols for these studies
must be evaluated carefully to ensure that the study design and animal model selected are
appropriate for the chemical being tested. In vitro methods that simulate the function of the
gastrointestinal tract are generally more robust than in vivo studies, and are rapid and relatively
inexpensive. Such studies have been validated by comparison with in vivo data for metals only,
although studies are currently underway to adapt an in vitro test system for use with semivolatile
organic compounds. Finally, simple leaching tests and mineralogical analyses may provide
useful information for risk management and selection of remediation options, but are not
expected to provide reliable quantitative bioavailability adjustments for use in deriving risk-
based cleanup levels.
For a number of organic and inorganic contaminants, sufficient data are available from
animal (in vivo) studies to provide default RAFs for these compounds in soil. Table E-1
provides a list of these default values, along with references to the studies on which they are
based. If a default RAF is not provided for a specific contaminant, or a more accurate (site-
specific) RAF is desired, a site-specific value may be derived using the methods discussed
below.
E - 7
Table E-1: Default RAFs for Oral Exposure to Contaminants in Soil
Contaminant RAF Basis
Arsenic 0.40 Freeman et al., 1993; 1995; USEPA (as cited in
Medlin, 1997)
Cadmium 0.50 Schoof and Freeman, 1995
Lead 0.60a Dieter et al., 1993; Freeman et al., 1992; USEPA
(as cited in Medlin, 1997)
Mercury 0.30b DOE, 1995; Smucker, 1994
PAHs 0.30 Magee et al., 1996b
TCDD 0.50 Shu et al., 1988
a Numerous studies in weanling animals have indicated that RAFs for lead in soil vary widely,
depending on the source and form of lead present. These results indicated that site-specific data is necessary
to justify the use of a value other than the default. use of the lead RAF for risk assessment requires
converting the RAF to absolute bioavailability for use in the Integrated Exposure Uptake Biokinetic Model
(IEUBK, see USEPA, 1994a) or the Adult Lead Model (see USEPA, 1996).
b
Value is applicable to soils that contain predominantly elemental mercury or mervuric sulfide.
Table E-2: References for the Design of Animal Models for Oral Bioavailability
Assessment
Element Animal Model Reference
Arsenic Monkeys
Swine
Freeman et al., 1995
Region VIII reference
Cadmium Rats Schoof and Freeman, 1995
Lead Weanling Rats
Weanling Swine
Freeman et al. 1992; Schoof et al., 1995
USEPA 1994b
Mercury Various Schoof and Nielsen, Risk Analysis, in press
PAHs Rats
Mice
Goon et al., 1990, 1991
Weyand et al., 1996
PCBs Rats [ref.]
Petroleum
Hydrocarbons
Mice Air Force study reference
TCDD Rats Shu et al., 1988
Example E-1 -- Adjustment of an Administered to an Absorbed Dose RfD
An oral Rfd, unadjusted for absorption, equals 10 mg/kg-day.
Other information (or an assumption) indicates a 20 percent oral absorption efficiency in
the species on which the RfD is based.
E - 8
The adjusted RfD that would correspond to the absorbed dose would be:
10 mg/kg-day x 0.20 = 2 mg/kg-day,
The adjusted RfD of 2 mg/kg-day would be compared with the amount estimated to be
absorbed dermally each day.
Example E-2 -- Adjustment of an Administered to an Absorbed Dose Slope Factor
An oral slope factor, unadjusted for absorption, equals (mg/kg-day) -1
.
Other information (or an assumption) indicated a 20 percent absorption efficiency in the
species on which the slope factor is based.
The adjusted slope factor that would correspond to the absorbed dose would be:
1.6 (mg/kg-day) -1
/ 0.20 = 8 (mg/kg-day) -1
.
The adjusted slope factor of 8 (mg/kg-day) –1
would be used to estimate the cancer risk
associated with the estimated absorbed dose for the dermal route of exposure.
Example E-3 -- Adjustment for Medium of Exposure
The daily oral intake of a chemical in soil is estimated to be 5 mg/kg-day.
The absorption of the chemical in drinking water is known to be 90 percent and the
absorption of the chemical from soil is measured to be 45 percent.
The relative absorption of the chemical in soil is 0.5 (i.e., the FAF = 0.45 / 0.90).
The oral intake of the chemical in soil may be adjusted by the RAF, to be comparable
with the oral toxicity factor (i.e., the RfD or cancer slope factor) which is based on an
administered dose in drinking water.
E.5 References
Dieter, M.P., H.B. Matthews, R.A. Jeffcoat, and R.F. Moseman. 1993.
Comparison Of Lead Bioavailability In F344 Rats Fed Lead Acetate, Lead Oxide,
Lead Sulfide, Or Lead Ore Concentrate From Skagway, Alaska. J. Toxicol.
Environ. Health 39:79–93.
DOE. 1995. Record of Decision for Lower East Fork Poplar Creek. DOE/OR/
02-1370&D1. US Department of Energy, Office of Environmental Restoration and
Waste Management. Prepared by Jacobs ER Team, Oak Ridge, TN.
E - 9
Freeman, G.B., J.D. Johnson, J.M. Killinger, S.C. Liao, P.I. Feder, A.O. Davis,
M.V. Ruby, R.L. Chaney, S.C. Lovre, and P.D. Bergstrom. 1992. Relative
Bioavailability Of Lead From Mining Waste Soil In Rats. Fund. Appl. Toxicol.
19:388–398.
Freeman, G.B., J.D. Johnson, J.M. Killinger, S.C. Liao, A.O. Davis, M.V. Ruby,
R.L. Chaney, S.C. Lovre, and P.D. Bergstrom. 1993. Bioavailability Of Arsenic In
Soil Impacted By Smelter Activities Following Oral Administration In Rabbits.
Fund. Appl. Tox. 21:83–88.
Freeman, G.B., R.A. Schoof, M.V. Ruby, A.O. Davis, J.A. Dill, S.C. Liao, C.A.
Lapin, and P.D. Bergstrom. 1995. Bioavailability Of Arsenic In Soil And House
Dust Impacted By Smelter Activities Following Oral Administration In
Cynomolgus Monkeys. Fund. Appl. Toxicol. 28:215–222.
Goon, D., N.S. Hatoum, J.D. Jernigan, S.L. Schmidt, and P.J. Garvin. 1990.
Pharmacokinetics And Oral Bioavailability Or Soil-Adsorbed Benzo[A]Pyrene
(Bap) In Rats. Toxicologist 10:218.
Goon, D., N.S. Hatoum, M.J. Klan, J.D. Nerniganm, and R.G. Farmer. 1991. Oral
Bioavailability Of “Aged” Soil-Adsorbed Benzo[A]Pyrene (Bap) In Rats.
Toxicologist 11:1356.
Hrudey, S.E., W. Chen, and C.G. Rousseaux. 1996. Bioavailability in
Environmental Risk Assessment. CRC Press, Inc., New York, NY.
Magee, B.H, A. Taft, W. Ratliff, J. Kelley, J. Sullivan, and O. Pancorbo. 1996a.
Physiologically Available Cyanide (PAC) in Manufactured Gas Plant Wastes and
Soil Samples. Abstract. 11th Annual Conference on Contaminated Soils,
University of Massachusetts at Amherst. October 21–24.
Magee, B., P. Anderson, and D. Burmaster. 1996b. Absorption Adjustment Factor
(AAF) Distributions For Polycyclic Aromatic Hydrocarbons (PAHs). Human Ecol.
Risk Assess. 2(4):841–873.
Medlin, E.A. 1997. An In Vitro Method For Estimating The Relative
Bioavailability Of Lead In Humans. Masters Thesis. Department of Geological
Sciences, University of Colorado at Boulder.
Ruby, M.V., A. Davis, R. Schoof, S. Eberle, and C.M. Sellstone. 1996. Estimation
Of Lead And Arsenic Bioavailability Using A Physiologically Based Extraction
Test. Environ. Sci. Technol. 30(2):422–430.
Schoof, R.A., M.K. Butcher, C. Sellstone, R.W. Ball, J.R. Fricke, V. Keller, and B.
Keehn. 1995. An Assessment Of Lead Absorption From Soil Affected By
Smelter Emissions. Environ. Geochem. Health 17(4):189–199.
E - 10
Schoof, R.A., and G.B. Freeman. 1995. Oral Bioavailability Of Lead And
Cadmium In Soil From A Smelter Site. Poster presented at the Seventh
International Congress of Toxicology, Seattle, Washington. July 3–6, 1995.
Shu, H., D. Paustenbach, F.J. Murray, L. Marple, B., Brunck, D. Rossi, and P.
Teitelbaum. 1988. Bioavailability Of Soil-Bound TCDD: Oral Bioavailability In
The Rat. Fund. Appl. Toxicol. 10:648–654.
Smucker, S. 1994. Memorandum to S. Hogan (December 1, 1994). Subject: Issue
Paper For Determination Of Site-Specific Cleanup Goal For Mercury In Residential
Soils. US Environmental Protection Agency, Region IX, San Francisco, CA.
USEPA. 1989. Risk Assessment Guidance for Superfund, Volume I: Human
Health Evaluation Manual (Part A). Interim Final. EPA/540/1-89/002. US
Environmental Protection Agency, Office of Emergency and Remedial Response,
Washington, DC.
USEPA. 1992. Dermal Exposure Assessment: Principles And Applications.
EPA/600/8-91/011B. US Environmental Protection Agency, Office of Research
and Development, Washington, DC.
USEPA. 1994a. Guidance Manual For The Integrated Exposure Uptake Biokinetic
Model For Lead In Children. EPA/540/R-93/081. US Environmental Protection
Agency, Office of Emergency and Remedial Response, Washington, DC.
USEPA. 1994b. Protocol For Systemic Availability Of Lead To Young Swine
From Subcronic Administration Of Lead-Contaminated Soil (Phase II). Ref:
8HWM-SM-TS. US Environmental Protection Agency, Region VIII, Denver,
Colorado.
USEPA. 1995. Assessing Dermal Exposure From Soil. US Environmental
Protection Agency, Region III, Office of Superfund Programs, Philadelphia, PA.
EPA/903-K-95-003.
USEPA. 1996. Recommendations Of The Technical Review Workgroup For Lead
For An Interim Approach To Assessing Risks Associated With Adult Exposures To
Lead In Soil. US Environmental Protection Agency, Technical Review Workgroup
for Lead.
Weyand, E.H., K. Rozett, A. Koganit, and R. Singh. 1996. Effect Of Soil On The
Genotoxicity Of Manufactured Gas Plant Residue. Fund. Appl. Toxicol. 30(1):
Part 2.
E - 11
APPENDEX E: ACRONYM LIST
ABS fractional absorption value
ATSDR Agency for Toxic Substances Disease Registry
CDI chronic daily intake
CSF cancer slope factor
IEUBK Integrated Exposure Uptake Biokinetic Model
IRIS Integrated Risk Information System
mg/kg-day milligrams per kilogram per day
PAH polycyclic aromatic hydrocarbons
PCB polychlorinated biphenyls
RAF relative absorption factor
RfD reference dose
SPLP Synthetic Precipitation Leaching Procedure
TCDD tetrachlorodibenzo-p-dioxin
TCLP Toxicity Characteristics Leaching Procedure
USEPA United States Environmental Protection Agency
F - 1
APPENDIX F: RISK ASSESSMENT FOR LEAD
F.1 Introduction
Risks for lead are assessed by comparing predicted blood lead levels to target blood lead
levels, rather than by calculating lifetime cancer risks (in the case of carcinogens), or comparing
predicted exposure to a Reference Dose (RfD) (in the case of non-carcinogens). Blood lead
levels are predicted based on environmental lead concentrations using either a childhood or an
adult model. Soil lead cleanup levels are calculated by selecting a target blood lead level and
doing a reverse calculation with the models to solve for soil lead concentration.
F. 2 Residential Exposure Scenarios
Children are the primary population of concern in residential exposure scenarios.
Children ingest more lead than do adults as a result of their frequent hand-to-mouth behavior,
they absorb more of the lead they ingest than do adults, and they are more sensitive to the effects
of lead than are adults. Blood lead levels for children are assessed for residential exposure
scenarios since protection of the childhood population alone assures the protection of the less-
susceptible adult population.
F.2.1 The USEPA Integrated Exposure Uptake Biokinetic Model for Children
The Integrated Exposure Uptake Biokinetic (IEUBK) Model (Version 0.99d) was
designed by the United States Environmental Protection Agency (USEPA) to estimate blood lead
levels in children up to age seven resulting from their exposure to lead in multiple environmental
sources, including diet, drinking water, air, and soil and dust. The Model contains four
components: exposure characterization, an absorption model, a biokinetics model, and
characterization of uncertainty or variability. Using estimates of lead concentrations in the
environment, the exposure component of the Model predicts the amount of lead taken into the
body that is then available in the gut or lungs for absorption. The absorption component
calculates the fraction of lead in the gut or lungs that is absorbed into the body’s circulatory
system. The biokinetic component modes the distribution of lead in the body among blood,
bone, liver, kidney, and other soft tissues and body fluids. Finally, the uncertainty and variability
component quantifies the extent to which blood lead levels may differ among children exposed
to the same environmental levels of lead. The IEUBK Model is also used to estimate acceptable
soil lead levels by choosing a target blood lead level, and, in effect, running the Model
“backwards” to derive a soil lead level that corresponds to that target.
F.2.2 Target Blood Lead Levels for Children
The USEPA recommends that environmental lead levels be limited to ensure that no
individual child has more than a 5% probability of having a blood lead level exceeding 10 g/dL
(USEPA, 1994a). This corresponds to a population median blood lead level below the target of
10 g/dL. The USEPA target blood lead level will be acceptable for the Voluntary Remediation
F - 2
and Redevelopment Act (VRRA) program. However, note that the Centers for Disease Control
(CDC) recommends (1) rescreening of children with blood lead levels between 10 and 14 g/dL
if a large proportion of children in a particular community have blood lead levels above 10
g/dL, (2) nutritional and education intervention for children with blood lead levels between 15
and 19 g/dL, with environmental investigation if blood lead levels persist in this range, and (3)
environmental evaluation and remediation only when a child’s blood lead level exceeds 20
g/dL (US CDC, 1991).
F.2.3 Exposure Parameters for Children
The USEPA Lead Guidance Manual (1994b) provides recommended values for all
exposure parameters required to calculate a distribution of blood lead levels for young children.
Discussed below are only those parameters relevant to the soil/dust ingestion pathway, and
recommend that USEPA guidance be followed for parameter values relevant to exposures
through diet or drinking water.
Soil lead concentrations – Generally four or more soil samples are taken from the
yard of a single residence. The required number of samples may be adjusted
based on potential site use and/or degree of homogeneity of the contamination.
Composite sampling is optional and may be helpful in providing adequate
coverage of large properties. The average lead concentration of these samples
should be used as input to the IEUBK Model for risk assessment purposes.
Dust lead concentrations – When measured interior residential house dust levels
are available, they can be used directly as input to the IEUBK Model. However,
dust levels may not have been measured, or in the case of new construction, will
not be available. In this situation, a soil-to-dust transfer coefficient can be used to
estimate dust lead levels as a function of soil lead levels. USEPA recommends a
soil-to-dust transfer coefficient of 0.7; that is, interior residential dust lead
concentrations are assumed to be 70% that of yard soil lead concentrations.
However, there are multiple potential sources of lead in interior dust, and a
transfer coefficient of 0.7 likely reflects sources of interior lead other than soil, an
assumption that can incorrectly inflate the apparent value of the transfer
coefficient. In the absence of other sources of lead, such as lead paint, or when
other sources make a small contribution to dust lead levels, a transfer coefficient
of 0.3 may be more appropriate. A transfer coefficient within the range of 0.3 to
0.7 is recommended, depending on age and conditioning of housing, and the
likelihood of additional sources of lead in dust. Justification should be given for
the chosen value.
Exposure frequency – The IEUBK Model was designed to assess uniform
exposures, meaning exposures that occur every day of the year. As such, there is
no explicit mechanism to deal with exposure frequency. However, the model can
be used to consider reduced exposure frequencies by calculating a weighted
average that reflects the fraction of each year during which a child is exposed to
soil and dust with different lead concentrations. For example, if a child spends 3
months in the summer at a residence with soil lead concentrations of 200 mg/kg,
F - 3
then the yearly average blood lead level arising from these exposures could be
assessed by using a soil lead concentration term equal to (1000)(3/12) +
(200)(9/12) = 400 mg/kg. This example assures both soils have the same lead
bioavailability. If not, then a weighting factor adjusting for alternate
bioavailabilities should also be included.
Soil/dust ingestion rates – USEPA recommends a combined soil and dust
ingestion rate that is age-dependent and ranges from 85 to 135 mg/day. The
agency also provides several alternative sets of values (see Table 2-7) if soil/dust
ingestion rates for children of a particular age are required.
The lower set of soil/dust ingestion rates should be used for sites where there may
be reason to suspect more limited soil and dust ingestion, such as at sites with full
grass cover. USEPA also recommends a default split between soil and dust
ingestion of 45% soil and 55% dust. The 45%-55% split may be adequate for
typical suburban or rural areas, but inner-city areas with little to no yard space
should more heavily weighted towards dust ingestion.
Soil/dust absorption – USEPA recommends a default soil and dust absorption
value for children of 0.3 or 30%. The model includes equations and parameters to
effect a non-linear relationship between absorption and increasing lead intake.
The default absorption value can be modified on the basis of site-specific
bioavailability information, such as would result from an in vivo or in vitro test
(Ruby, et al. 1996)
Geometric standard deviation – The individual geometric standard deviation
(GSD) is the parameter used to estimate the probability that an individual’s blood
lead level exceeds 10 g/dL given the Model-predicted geometric mean blood
lead level for the designated environmental exposures. USEPA currently
recommends a value of 1.6. However, this value, which quantifies the spread in
blood lead levels assuming exposure to uniform levels of lead in soil and dust, is
quite high given that community-wide blood lead GSD values, which reflect a
range of exposure conditions (e.g., a range of soil and dust lead levels) are often
not much higher than 1.6. USEPA has recently estimated site-specific GSDs for
the communities of Bingham Creek and Sandy Utah (USEPA, 1995a,b) of 1.43
and 1.4, respectively. It is recommended that the individual GSD be chosen from
a range of 1.4 to 1.6, with justification given for the chosen value.
F.3 Commercial/Industrial Exposure Scenarios
Although evaluation of lead risks usually centers on children, there are situations in
which adults may be exposed to elevated levels of lead in the environment where children are
unlikely to be exposed. For example, adult blood lead levels should be assessed for commercial
and industrial exposure scenarios. Of adults, the population of most concern is women of child-
bearing age because of the transfer of lead from pregnant mother to fetus.
F - 4
F.3.1 The Adult Model
The USEPA (1996) recommends estimation of adult blood lead levels using an approach
based on an adult blood lead model developed by Bowers, et al 1994). This Model is similar to
the IEUBK Model used for children in that it also contains the same four components (exposure,
absorption, biokinetics, and uncertainty or variability). However, the biokinetic portion of this
Model consists of a single biokinetic slope factor that relates lead uptake to blood lead.
Additionally, rather than assessing lead exposures to adults from all sources, the Model focuses
on exposure to soil and dust and uses a “baseline” blood lead level to represent the contributions
of all other sources of lead, including past exposures. Equations for the adult model are given in
Table F-1, together with an example calculation. The adult model is also used to estimate
acceptable soil lead levels by running the model “backwards” to calculate a soil lead level that
corresponds to a target blood lead level.
F.3.2 Target Blood Lead Levels for Adults
The USEPA recommends a target blood lead level for women of child-bearing age to
ensure that the fetus has no more than a 5% probability of a blood lead level exceeding 10 g/dL
(USEPA, 1996). The ratio of fetal to maternal blood lead levels is about 0.9. Therefore, a
woman of child-bearing age should have no more than a 5% probability of having a blood lead
level exceeding 11.1 g/dL (i.e., 10 divided by 0.9).
F.3.3 Exposure Parameters for Adults
The USEPA (1996) recommends values for all parameters in the adult model. Values
recommended here are based on the best available information; however, some values differ
from USEPA’s recommendations.
Soil lead concentrations - Soil samples should be averaged over the exposure
area and the arithmetic mean used as input to the adult model.
Dust lead concentrations – Interior dust lead levels are generally not available in
occupational settings, but can be estimated using a soil-to-dust transfer
coefficient. If dust levels are available, they can be averaged and used directly in
the model. If they are not available, a soil-to-dust transfer coefficient in the range
of 0.3 to 0.7 can be used. A value in this range should be chosen based on the
likelihood that there are other sources of lead besides site soils that contribute to
interior dust lead levels, e.g., lead paint.
Exposure frequency – Exposure frequency should be based on site-specific
information. In the absence of site-specific information, a value of 250 days/year
can be used, reflecting the assumption that individuals typically work 5 days a
week for 50 weeks of the year.
F - 5
Soil/dust ingestion rates – Little information is available concerning the amount
of soil and dust that adults ingest, although it is likely that adults ingest less than
do children. Bowers and Cohen (1997) recommend 0.02 g/day as an average
adult ingestion rate, while USEPA recommends 0.05 g/day, both of which assume
an eight hour/day exposure. A value in this range may be used. The soil/dust
ingestion rate should be considered the average rate for an adult during their
waking hours, and thus this rate may be reduced to reflect the fraction of time that
the adult spends on the site, if appropriate. Activities which involve heavy dust
generation, e.g. heavy construction, may warrant a higher ingestion rate. See
USEPA 1991b, Section 3.
Soil/dust absorption – The fraction of lead in ingested soil and dust absorbed into
the circulatory system is the product of two values: the amount of soluble lead
absorbed and the ratio of this fraction for lead in soil and dust to the
corresponding fraction for soluble lead. Data presented in James et al (1985)
indicate that absorption of soluble lead can range from approximately 60% after a
prolonged period of fasting to approximately 4% at mealtime. A time-average
absorption of soluble lead that takes account of meal times and times between
meals will fall close to the low end of this range. Current estimates of the time-
averaged fraction of soluble lead absorbed for adults ranges from 8% (O’Flaherty
(1993) to 20%). (EPA (Marjo to complete cite)). Note: Current literature should
be consulted for updates of this range. This absorption value can be modified on
the basis of site-specific bioavailability information, such as would result from an
in vivo or in vitro test (Ruby, et al. 1996).
Baseline blood lead level – USEPA recommends a baseline blood lead level for
women of child-bearing age of 1.7 to 2.2 g/dL. This blood lead level represents
individuals who are not exposed to substantial sources of lead beyond
background, and the range is indicative of diverse conditions across the United
States (U.S.). The National Health and Nutrition Evaluation Study (NHANES) III
data set (Pirkle et al 1994) indicates that the geometric mean blood lead level for
women of child-bearing age (defined as age 20 to 40) in the southern region of the
US is 1.54 g/dL.
Biokinetic slope factor – USEPA recommends a biokinetic slope factor of 0.4
g/dL blood lead per g/day lead intake.
Geometric standard deviation – The individual GSD is the parameter used to
estimate the probability that an individual’s blood lead level exceeds 10 g/dL (or
another target blood lead level) given the Model-predicted geometric mean blood
lead for the designated environmental exposures. The NHANES III data set
indicates that for women of child-bearing age (defined as age 20 to 40) in the
southern region of the US, the GSD is 1.88. However, this GSD reflects blood
lead variation due to differences in soil and dust lead concentrations across the
broad geographical region of the south. At individual sites, heterogeneity in
blood lead levels can be expected to be substantially less than across broad
geographic regions because the range of exposures will not be as broad. To
account for the tendency for site-specific GSDs to be smaller than GSDs for
F - 6
populations living over a broad geographic region, we recommend that a value
less than 1.88, such as 1.7, be used. This value can be chosen from a range of 1.6
to 1.8. A value of 1.7 is used as an example to illustrate calculation of a cleanup
level in Table F-1.
Table F-1: Equation and Parameters for the Adult Blood Lead Model
PbB PbB BSF I AEF
f C f Cadult baseline s s d d 365
( )
PbB PbB R GSDth adult fetal adult95
1 645 /
.
Parameter Description Value
PbB95th
95th
percentile fetal blood lead level
(substitute target blood lead level
when calculating an acceptable soil
lead level
95th
percentile is calculated,
target for children is 10 g/dL
PbBadult central estimate of adult blood lead
level
calculated
PbBbaseline baseline adult blood lead level 1.54 (women of child-bearing
age)
Rfetal/adult ratio of fetus to maternal blood lead 0.9
GSD geometric standard deviation of adult
blood lead
1.7
BSF biokinetic slope factor 0.4 g/dL per g/day
I soil/dust ingestion rate 0.05 g/day
A absorption of lead from soil/dust 0.048
EF exposure frequency 250 days
fs fraction of soil ingested based on site usage
Cs concentration of lead in soil site-specific, or calculated when
target blood lead level is
specified
fd fraction of dust ingested, = 1-fs based on site usage
Cd concentration of lead in dust site-specific, or calculated from
a soil-to-dust transfer coefficient
Example Calculation of a Soil Lead Cleanup Level
Set fs = fd = 0.5, Cd = (0.3)(Cs)
10 09 17 4 641 645 ( )( . )( . ); . /.PbB PbB g dLadult adult
4 64 154 0 4 0 05 0 048250
36505 05 0 3 7253. . ( . )( . )( . )( )(( . )( ) ( . )( . )( )); / C C C mg kgs s s
F - 7
F.4 References
Bowers, T.S., B.D. Beck, and H.S. Karam. 1994. Assessing The Relationship
Between Environmental Lead Concentrations And Adult Blood Lead Levels.
Risk Analysis. 14:183-189.
Bowers, T.S. and J.T. Cohen. 1997. Blood Lead Slope Factor Model For Adults:
Comparisons Of Observations And Predictions. Proc. Vol. Of 1996 EPA Lead
Model Validation Workshop, in press.
James, H.M., M.E. Hilburn, J.A. Blair. 1985. Effects Of Meals And Meal Times
On Uptake Of Lead From The Gastrointestinal Tract In Humans. Human
Toxicol. 4:401-407.
O’Flaherty, E.J. 1993. Physiologically Based Models For Bone-Seeking
Elements. IV. Kinetics Of Lead Disposition In Humans. Toxicol. Appl.
Pharmacol. 118:16-29.
Pirkle, J.L., D.J. Brody, E.W. Gunter, R.A. Kramer, D.C. Paschal, K.M. Flegal,
and T.D. Matte. 1994. The Decline In Blood Lead Levels In The United States:
The National Health and Nutrition Examination Surveys (NHANES). JAMA
272:284-291.
Ruby, M.W., A. Davis, R. Schoof, S. Eberle, and C.M. Sellstone. 1996.
Estimation Of Lead And Arsenic Bioavailability Using A Physiologically Based
Extraction Test. Environ. Sci. Technol. 30:422-430.
US Centers for Disease Control (CDC). 1991. Preventing Lead Poisoning In
Young Children. US Dept. of Health and Human Services, October.
US Environmental Protection Agency (USEPA). 1994a. Revised Interim Soil
Lead Guidance For CERCLA Sites And RCRA Corrective Action Facilities,
Office of Solid Waste and Emergency Response, Directive 9355.4-1, July 14.
US Environmental Protection Agency (USEPA). 1994b. Guidance Manual for
the Integrated Exposure Uptake Biokinetic Model for Lead in Children. Office of
Emergency and Remedial Response. Pub. No. 9285.7-15-1, EPA/540/R-93/081,
February.
US Environmental Protection Agency (USEPA). 1995a. Site-specific Integrated
Exposure Uptake Biokinetic Modeling, Kennecott Baseline Risk Assessment
prepared by Life Systems, Inc. June.
US Environmental Protection Agency (USEPA). 1995b. Evaluation Of The Risk
From Lead And Arsenic, Sandy Smelter Site – Sandy, Utah – December.
US Environmental Protection Agency (USEPA). 1996. Recommendations Of
The Technical Review Workgroup For Lead For An Interim Approach To
Assessing Risks Associated With Adult Exposures To Lead In Soil. December.
F - 8
APPENDIX F: ACRONYM LIST
g/dL micrograms per deciliter
CDC Center for Disease Control
g/day grams per day
GSD geometric standard deviation
IEUBK Integrated Exposure Uptake Biokinetic Model
mg/day milligrams per day
mg/kg/day milligrams per kilogram per day
NHANES National Health and Nutrition Evaluation Study
RfD reference dose
USEPA United States Environmental Protection Agency
VRRA Voluntary Remediation and Redevelopment Act
G - 1
APPENDIX G: REFERENCES TO BENCHMARK SCREENING LEVELS
Eisler, R. 1988. Lead Hazards To Fish, Wildlife, And Invertebrates: A Synoptic Review. US
Fish and Wildlife Service Patuxent Wildlife Research Center, Laurel, MD. US Department of
the Interior. Biological Report 85 (1.14), Contaminant Hazard review Rep. No. 14.
Grossman, G.D. 1990. Assemblage Stability In Stream Fishes: A Review. Environmental
Management. 14:661-667.
Jones, D.S., R.N. Hull, and G.W. Suter II. 1996. Toxicological Benchmarks For Screening
Contaminants Of Potential Concern For Effects On Sediment-Associated Biota: 1996 Revision.
Oak Ridge National Laboratories, Oak Ridge, TN. 34 p., ES/ER/TM-95/R2.
Ontario Ministry of the Environment. 1993. Guidelines For The Protection And Management
Of Aquatic Sediment Quality In Ontario. Water Resources Branch. ISBN 0-7729-9248-7.
Pascoe, G.A. 1994. Characterization Of Ecological Risks At The Milltown Reservoir-Clark
Fork River Sediments Superfund Site, Montana. Environmental Toxicology and Chemistry.
13:1-16.
Sample, B.E., D.M. Opresko, and G.W. Suter. 1996. Toxicological Benchmarks For Wildlife:
1996 Revision. Oak Ridge National Laboratories, Oak Ridge, TN. 227 p., ES/ER/TM-86/R3.
Suter, G.W. 1995. Toxicological Benchmarks For Screening Contaminants Of Potential
Concern For Effects On Freshwater Biota. Environmental Toxicology and Chemistry. 15:1232-
1241.
Suter, G.W. II, and C.L. Tsao. 1996. Toxicological Benchmarks For Screening Of Potential
Contaminants Of Concern For Effects On Aquatic Biota On Oak Ridge Reservation: 1996
Revision. Oak Ridge National Laboratories, Oak Ridge, TN. 104 p., ES/ER/TM-96/R2.
Stephan, C.E., et al. 1985. Guidelines For Deriving Numeric National Water Quality Criteria
For The Protection Of Aquatic Organisms And Their Uses. PB85-227049. US Environmental
Protection Agency, Washington, DC.
US Environmental Protection Agency. 1996. Ecotox Thresholds. Intermittent Bulletin;
Volume 3, Number 2. EPA/540/F-95/038.
Will, M.E. and G.W. Suter. 1995. Toxicological Benchmarks For Screening Potential
Contaminants Of Concern For Effects On Terrestrial Plants: 1995 Revision. Oak Ridge
National Laboratories, Oak Ridge, TN. 123 p., ES/ER/TM-85/R2.
Will, M.E. and G.W. Suter. 1995. Toxicological Benchmarks For Potential Contaminants Of
Concern For Effects On Soil And Litter Invertebrates And Heterotrophic Process. Oak Ridge
National Laboratories, Oak Ridge, TN. 155 p., ES/ER/TM-126/R1.
If none of the above references fit the screening needs of a particular project, LRS can
consult EPA’s Ecological Effects Test Guidelines – Series 850, a guidance on toxicity testing to
G - 2
develop benchmark screening levels. The most recent version with supporting documentation
can be found on the internet at http://www.hsrd.ornl.gov/ecorisk/ecorisk.html.
H - 1
APPENDIX H: SITE SPECIFIC RISK ASSESSMENT
H.1 Risk Assessment Equations and Parameters
This section briefly outlines the standard equations used to calculate intake of
contaminants in various media. The equations in this section can be used for so-called “point-
estimate” risk assessments, where each parameter in the equation is replaced with a single value
(the “point estimate”), and the equation yields a single estimate of risk. “Intake” is expressed in
terms of mg/kg-day. In the case of cancer risks, this value reflects a lifetime average. The
product of the intake value and the cancer slope factor for a contaminant is the lifetime risk of
cancer. In the case of noncancer risks, the intake value reflects the average over a “chronic”
exposure period, typically defined to be seven years or longer. The ratio of the intake value to a
contaminant’s reference dose is the hazard index. Exposures corresponding to a hazard index
less than 1.0 are considered to be without appreciable risk, even among susceptible sub-
populations. If the hazard index exceeds 1.0, exposure may be sufficient to cause adverse health
effects.
The generic equation for intake, denoted I (as outlined by USEPA, 1989, Exhibit 6-9), is
I CCR EFD
BW AT
1
Where:
C = Chemical concentration; the average concentration contacted over the
exposure period (e.g., mg/L water).
CR = Contact rate; the amount of contaminated medium contacted per unit of
time or event (e.g., L/day).
EFD = Exposure frequency and duration; describes how often and for how long
exposure occurs. Often calculated using two terms (EF, or “exposure
frequency,” reported in days/year, and ED, or “exposure duration,”
reported in years).
BW = Body weight; the average body weight over the exposure period (kg).
AT = Averaging time; period over which exposure is averaged (days).
The quantity C is a chemical-specific parameter. The quantities CR, EFD, and BW are
parameters that describe the exposed population. The parameter AT is a fixed quantity whose
value depends on whether risk being evaluated is carcinogenic or non-carcinogenic.
The remainder of this section details intake equations for the following exposure
scenarios:
Ingestion of chemicals in water
Dermal contact with chemicals in water
H - 2
Ingestion of chemicals in soil
Dermal contact with chemicals in soil
Inhalation of airborne chemicals
Ingestion of fish
Additional exposure pathways may be considered in a site-specific risk assessment, for
example, see USEPA (1997).
H.1.1 Ingestion of Chemicals in Water
The United States Environmental Protection Agency (USEPA) (1989) quantifies intake
of chemicals in water via ingestion in Exhibit 6-11 of the Agency’s document. Specifically,
intake is calculated as:
ICW IRW EF ED
BW AT
Where:
CW = Chemical concentration in water (mg/L)
IRW = Ingestion rate of water (liters/day)
EF = Exposure frequency (days/year)
ED = Exposure duration (years)
BW = Body weight (kg)
AT = Averaging time (days)
This equation is applicable to ingestion of any source of water, including tap water, or,
for example, surface water ingested while swimming.
H.1.2 Dermal Contact with Chemicals in Water
USEPA (1989) quantifies intake of chemicals via dermal contact with water in Exhibit 6-
13 of the Agency’s document. Specifically, intake is calculated as:
ICW SA PC ET EF ED CF
BW AT
Where:
CW = Chemical concentration in water (mg/L)
SA = Skin surface area available for contact (cm2)
PC = Chemical-specific dermal permeability constant (cm/hr)
ET = Exposure time (hours/day)
EF = Exposure frequency (days/year)
ED = Exposure duration (years)
CF = Volumetric conversion factor (l L/1000 cm3
)
H - 3
BW = Body weight (kg)
AT = Averaging time (days)
This equation is applicable to dermal contact of any source of water, including tap water,
or, for example, surface water in which an individual comes into contact while swimming.
H.1.3 Ingestion of Chemicals in Soil
USEPA (1989) quantifies intake of chemicals via ingestion of soil in Exhibit 6-14 of the
Agency’s document. Specifically, intake is calculated as:
ICS IRS CF FI EF ED
BW AT
Where:
CS = Chemical concentration in soil (mg/kg)
IRS = Ingestion rate for soil (mg soil/day)
CF = Conversion factor (10-6
kg/mg)
FI = Fraction ingested from contaminated source (unitless)
EF = Exposure frequency (days/year)
ED = Exposure duration (years)
BW = Body weight (kg)
AT = Averaging time (days)
H.1.4 Dermal Contact With Chemicals in Soil
USEPA (1989) quantifies intake of chemicals via dermal contact with soil in Exhibit 6-15
of the Agency’s document. Specifically, intake is calculated as:
ICS CF SA AF ABS ED EF
BW AT
Where:
CS = Chemical concentration in soil (mg/kg)
CF = Conversion factor (10-6
kg/mg)
SA = Skin surface area available for contact (cm2
/ event)
AF = Soil to skin adherence factor (mg/cm2
)
ABS = Chemical specific absorption factor (unitless)
EF = Exposure frequency (events/year)
ED = Exposure duration (years)
BW = Body weight (kg)
AT = Averaging time (days)
H - 4
H.1.5 Inhalation of Airborne Chemicals
USEPA (1989) quantifies intake of chemicals via inhalation in Exhibit 6-16 of the
Agency’s document. Specifically, intake is calculated as:
ICA IRA ET EF ED
BW AT
Where:
CA = Contaminant concentration in air (mg/m3
)
IRF = Average ingestion rate for fish (g/day)
CF = Conversion factor (10-3
kg/mg)
FI = Fraction ingested from contaminated source (unitless)
EF = Exposure frequency (days/year)
ED = Exposure duration (years)
BW = Body weight (kg)
AT = Averaging time (days)
H.1.6 Ingestion of Fish
Intake of contaminants from fish is calculated as (USEPA, 1989):
ICF IRF CF FI EF ED
BW AT
Where:
CS = Chemical concentration in fish (mg/kg)
IRF = Average ingestion rate for fish (g/day)
CF = Conversion factor (10-3
kg/mg)
FI = Fraction ingested from contaminated source (unitless)
EF = Exposure frequency (days/year)
ED = Exposure duration (years)
BW = Body weight (kg)
AT = Averaging time (days)
It should be noted that the USEPA recommended default value for fish ingestion rate
(USEPA, 1997) is the daily intake averaged over a year (not the average amount of fish
consumed per meal), and thus should be used in conjunction with an exposure frequency of 365
days/year.
H.1.7 Additional Pathways
Additional pathways should be considered in the risk assessment where appropriate for
the site. These pathways include:
Dermal and inhalation exposure to an adult while showering. (USEPA
recommends the use of the Foster and Chrostowski Model for determining
inhalation exposure in the shower.)
H - 5
Dermal exposure to a child while bathing
Inhalation of volatiles and particulates from soil
Dermal contact with water while swimming
Dermal contact with surface water while wading
Ingestion of homegrown fruits and vegetables
Soil contact by a construction worker (ingestion, inhalation, and dermal
contact)
It is recommended that the risk assessor consult the USEPA Exposure Factors Handbook
(USEPA, 1997) to determine the appropriate input parameters for a given exposure pathway.
H.2 Conservative Parameter Values for a Point Estimate Risk Assessment
One approach to the selection of conservative point estimate values is to use values that
USEPA has identified as corresponding to the “Reasonable Maximum Exposure,” or “RME.”
USEPA defines the RME “as the highest exposure that is reasonably expected to occur at a site
(USEPA, 1989, p 6-4). Although the USEPA notes that estimation of the RME may involve
professional judgment, the Agency provides values for some exposure parameters that, according
to USEPA, are appropriate for this calculation. USEPA also cautions that, “The specific values
identified should be regarded as general recommendations, and could change based on site-
specific information...” (USEPA, 1989, p 6-5). Table H-1 summarizes the parameter values
recommended by USEPA.
H - 6
Table H-1: Parameter Values Recommended by USEPA
Parameter
Water
Ingestion
Water:
Dermal
Contact
Soil
Ingestion
Soil:
Dermal
Contact
Inhalation
IR 2.32 L/daya
1.4 L/dayb
1.3 L/dayc
0.74 L/dayd
200 mg/dayfd
100 mg/dayge
30 m3 / day
f
20 m3 / day
hg
10 m3 / day
i
0.6 m3 / hr
jh
50 ml/hourec
AF 1.45 mg / cm2
ET 12 minuteski
8 minuteslj
20 minutesm
Parameters that do not differ by Exposure Pathway
EF 350 days/yr or pathway dependent, depending on the nature of the exposure
scenario
ED 70 years (lifetime exposure)
30 years (national 90th
percentile duration for living at one location)
9 years (national median duration for living at one location)
BW 70 kg (adult)
16 kg (child aged 1 to 6 years)
Age-specific data
SA See table H-2, different combination of arms, hands, and legs may be
appropriate for different exposure pathways
FI Fraction of ingestion soil from contaminated site: Exposure and pathway
scenario specific
Parameters for Additional Pathways
IR (fish) 8 g/day (Mean)
25 g/day (95th
Percentile)
(Fish consumption by Recreational Freshwater Anglers (USEPA, 1997))
ED (swimming) 60 mins/event (50th
percentile) (USEPA, 1997)
180 mins/event (90th
percentile) (USEPA, 1997)
EF (swimming) 1 event/month (average, adult) (USEPA, 1997)
ED (construction
worker) 25 years or site-specific
EF (construction
worker) 250 days/yr or site-specific
H - 7
Source: U.S. EPA, 1989, Exhibits 6-11, 6-12, 6-13, 6-14, 6-15, 6-16, except where otherwise
noted.
Notes:
a. Adult, 90th
percentile (USEPA, 1997, Table 3-30)
b. Adult, average (USEPA, 1997, Table 3-30)
c. Child, 1-10 yr, 90th
percentile (USEPA, 1997, Table 3-30)
d. Child, 1-10 yr, average (USEPA, 1997, Table 3-30)
b. Adult, average
ec. Ingestion rate while swimming
fd. Children, 1-6 years old, upper bound value
ge. Adult upper bound value
f. Adult upper bound value
g. Adult, average
h. Adult, average
i. Child, average
jh. Inhalation rate while showering
ki. Showering, 90th
percentile duration
lj. Showering, average duration. (USEPA, 1997).
m. Bath duration, recommended value for all ages (USEPA 1997 Table 15-176)
USEPA recommends that when calculating the RME value, the 90th
or 95th
percentile
values specified in Table H-1 should be used. For the purpose of conducting a Tier I point-
estimate screening assessment, it is recommended that this guidance be followed.
Body surface area values for the 50th
percentile individual appear in Table H-2 (USEPA,
1989, Exhibit 6-15). Based on USEPA’s guidance, it is recommended that these values be used
when conducting a Tier I point-estimate screening assessment.
Table H-2: 50th
Percentile Body Surface Area
Total Body Surface Area (m2): 50
th Percentile
Age (Years) Male Female
3 < 6 0.728 0.711
6 < 9 0.931 0.919
9 < 12 1.16 1.16
12 < 15 1.49 1.48
15 < 18 1.75 1.60
Adult 1.94 1.69
Body-Part Specific Surface Area (m2): 50
th percentile
Age (Years) Arms Hands Legs
3 < 4 0.096 0.040 0.18
6 < 7 0.11 0.041 0.24
9 < 10 0.13 0.057 0.31
Adult 0.23 0.082 0.55
H - 8
In addition to the population-specific parameters described in the Tables H-1 and H-2,
there are several chemical-specific values that must be quantified. In general, use of the average
or median value for each of these parameters is recommended.
One parameter – the chemical concentration – is both chemical-specific and site-specific.
Following USEPA’s guidance, it is recommended that the 95 percent upper confidence limit on
the arithmetic mean be used as the chemical concentration. Calculation of the upper confidence
limit on the mean depends on whether the observations follow a normal distribution or a
lognormal distribution. USEPA (1992) has disseminated guidance outlining calculation of the
95% upper confidence limit on the mean in both of these cases.
H.3 References
US Environmental Protection Agency (USEPA). 1989. Risk Assessment
Guidance for Superfund. Volume II: Environmental Evaluation Manual. Office
of Emergency and Remedial Response (Washington, DC). EPA-540/1-89-001.
March.
US Environmental Protection Agency (USEPA). 1992. Office of Solid Waste
and Emergency Response (Washington, DC). Supplemental Guidance to RAGS:
Calculating the Concentration Term. OSWER Publication 9285.7-081; NTIS
PB92-963373. 8p. May 1992.
US Environmental Protection Agency (USEPA). 1997. Office of Health and
Environmental Assessment, Exposure Assessment Group. Exposure Factors
Handbook – Volumes I, II and III. EPA/600/P-97/002FA,B,C.
APPENDIX H: ACRONYM LIST
ABS chemical specific absorption factor
AF soil to skin adherence factor
AI annual intake
AT averaging time
BW body weight
C chemical concentration
CA contaminant concentration in air
CF volumetric conversion factor
cm2
square centimeters
cm3
cubic centimeters
cm/hr centimeters per hour
CR contact rate
H - 9
CRG cleanup remediation goal
CS chemical concentration in soil
CSF cancer slope factor
CW chemical concentration in water
DIR daily intake rate
ED exposure duration
EF exposure frequency
EFD exposure frequency and duration
ET exposure time
ETshoer exposure time for bathing
FI fraction ingested from contaminated source
GM geometric mean
GSD geometric standard deviation
hr hour
IRAir inhalation rate for air
IRSoil ingestion rate for soil
IRWater ingestion rate for water
kg kilogram
L liter
m2
square meter
m3
cubic meter
mg milligram
ml milliliter
PC chemical-specific dermal permeability constant
R ratio
RfD reference dose
RME Reasonable Maximum Exposure
SA skin surface area
SES socio-economic status
SPLP Synthetic Precipitation Leaching Procedure
USEPA United States Environmental Protection Agency
I - 1
APPENDIX I: PROBABILISTIC METHODOLOGIES IN RISK ASSESSMENT
I .1 Tiered Approach to the Use of Probabilistic Risk Assessment
The risk equations provided in Appendix H can also be used for probabilistic risk
assessments as well as “point-estimate” risk assessments. In the latter case, each value in the
equation is replaced with a single value (the “point estimate”), and the equation yields a single
estimate of risk. A probabilistic risk assessment characterizes each parameter by a probability
distribution, which places positive weight on each plausible value for that parameter. The risk
estimate generated by a probabilistic risk assessment is also a probability distribution, describing
the range of plausible risk estimates for the population of interest, as well as the relative
frequency for each risk value. This information can inform the risk manager as to the fraction of
the population subject to risks exceeding a specified threshold, as well as the degree of certainty
associated with these estimates. Section I.2 discusses the nature and use of the risk values
generated by a probabilistic analysis in greater detail.
Although probabilistic risk assessment provides more information than a point-estimate
risk assessment, it requires more information to execute. It is also far more computationally
intensive, typically requiring specialized (though easily available) software, and, depending on
the degree of sophistication, the development of assessment-specific computer programs. It is
therefore desirable to develop point-estimate risk assessments as a first step in such a way that, in
some cases, they make the execution of a probabilistic assessment unnecessary.
Recall that a probabilistic risk assessment can quantify the fraction of individuals
exceeding a specified risk threshold, along with the degree of certainty associated with that
estimate. Such information is unnecessary if you can determine from a point estimate risk
assessment that it is likely that only a very small fraction of the members in a population will
incur health risks exceeding some threshold of interest. In order to reach such a conclusion using
a point estimate risk assessment, it is necessary to assign a sufficient number of parameters
“conservative” (meaning health-protective) values. If the point estimate risk calculated on the
basis of these assumptions is below the risk threshold of interest, then the risk manager can
conclude that, with a sufficient level of confidence, members of the population, will not, for the
most part, be subject to unacceptable risks. In this situation, it is unnecessary to conduct a
probabilistic assessment.
However, if the conservative point estimate assessment yields an unacceptable risk value,
it cannot be concluded that populations’ risks are, in reality, unacceptable. In this case, the
calculated risk estimate may be too high because either the risks really are unacceptable, or
because the use of conservative parameter assumptions have inflated what would have been
considered an acceptable risk. Since it is impossible to tell which of these explanations is true, it
is necessary to conduct a probabilistic assessment to generate more detailed information about
the nature of the risks to which the population is subjected.
In summary, the tiered approach calls for the risk assessor to first conduct a point
estimate assessment using conservative values for selected parameters, as outlined in Appendix
H. If that assessment yields an acceptable risk, the risk manager can conclude that risks are
acceptable. No further computations are necessary. However, if the point estimate is
I - 2
unacceptable, the risk assessor may proceed to the second tier, which involves execution of a
probabilistic assessment.
I .2 Probabilistic Risk Assessment
This section describes Monte Carlo simulation, a technique used to conduct Tier II
probabilistic risk assessments. Section I.2.1 discusses the concepts of “variability” and
“uncertainty.” These concepts are key to development of valid parameter distributions for a
Monte Carlo simulation, and to the proper interpretation of the risk estimates from such a
simulation. Section I.2.2 then describes how Monte Carlo simulation works and how to interpret
the results of a Monte Carlo simulation.
I .2.1 Uncertainty and Variability
Monte Carlo risk assessment allows parameters to be assigned more than one value.
However, the possibility of assigning more than one value to a parameter can reflect either or
both of two phenomena, referred to as “uncertainty” and “variability.” At an USEPA workshop
on the subject of Monte Carlo analysis conducted during May of 1996 (USEPA, 1996),
variability and uncertainty were defined as follows:
Variability represents the natural heterogeneity or diversity in a well-characterized
population. Variability:
- Usually not reducible through further measurement or study.
- Is a property of the population.
- Reflects physical, chemical, and biological phenomena
Uncertainty represents ignorance (or lack of perfect knowledge) about poorly
characterized phenomena or models. Uncertainty:
- May sometimes be reducible through further measurement or study.
- Is a property of the analyst.
- Reflects limitations of our understanding of the physical world.
Body weight is an example of a quantity that varies across members of the population but
for which uncertainty is not substantial. A probability distribution for body weights places
weight on each value that is proportional to the frequency with which is thought to occur in the
population.
On the other hand, the average concentration of a contaminant in an exposure unit does
not vary (there is one true value that holds for all members of the population), but which can be
uncertain due to finite sampling of that quantity. In this case, the distribution characterizing this
I - 3
quantity places weight on alternative values that are proportional to each alternative’s
plausibility. The weight on all values between two endpoints divided by the weight placed on all
values is equal to the probability that the true value lies between the specified endpoints.
Finally, there are quantities that are both uncertain and variable. This case is the most
complex. For example, it is reasonable to suspect that the soil ingestion rate varies among
children. It is also true that this quantity is very difficult to measure, making it uncertain.
Characterization of both uncertainty and variability requires specification of multiple probability
distributions, each representing one possible characterization of variability in the population.
The fact that there are multiple distributions is a manifestation of the quantity’s uncertainty. For
example, consider the 95th
percentile value for each of the alternative distributions. In general,
these values differ. Together, they represent the uncertainty distribution for the 95th
percentile
for the parameter. Likewise, the collection of alternative arithmetic mean values represents the
uncertainty distribution for the arithmetic mean for the parameter. It is important to note that a
one-dimensional Monte Carlo analysis can characterize either uncertainty or variability. If the
input probability distribution functions (PDFs) contain both uncertainty and variability, then the
result can not be interpreted as either. For this reason, uncertainty and variability should not be
combined in a one-dimensional Monte Carlo analysis.
I .2.2 Overview of Monte Carlo Technique
Conceptually, Monte Carlo simulation is straight-forward. Suppose one wishes to
characterize a distribution of annual intake values (mg/year) for a population given that annual
intake (AI) for a specific individual is the product of two quantities: EF (days/year), and the
daily intake rate (DIR) when the individual is exposed to contaminant of concern (mg/day).
Suppose that the distribution for EF is uniform between 225 days/year and 275 days per year,
and that the DIR is lognormally distributed with a geometric mean of 30 mg/day and a geometric
standard deviation of 2.0. Monte Carlo simulation characterizes the distribution for the annual
intake by first selecting a value at random from the distribution characterizing EF, then selecting
a value at random from the distribution characterizing DIR, and multiplying them together. This
product is a single estimated value of AI. The simulation then repeats this process, generating a
second value for AI. After repeating this process many times (e.g., 1,000 or 10,000 times), the
simulation has generated a large number of values for AI. Monte Carlo simulation has the
property of producing a set of values that approximates the “true” distribution for the calculated
quantity (in this case, AI), assuming that the distributions chosen for the parameters are valid,
and that the relationship between the parameters and the calculated quantity is valid.
The simulation described in the preceding paragraph is referred to as a “one-stage”
simulation. A one-stage simulation is sufficient when the risk assessor can assume that either the
parameter distributions all represent variability, or all represent uncertainty. In the former case
(all the parameter distributions represent variability), the distribution of values produced by the
Monte Carlo simulation represents variability. For example, if a simulation generates 1,000
exposure values, and these values are ranked from smallest to largest, then the 950th
value is an -
+estimate of the 95th
percentile of the population exposure distribution. The 500th value is an
estimate of the 50th percentile of the population exposure distribution. In the latter case (all the
parameter distributions represent uncertainty), the distribution of values produced by the Monte
Carlo simulation represents uncertainty. For example, the 950th value is an estimate of the upper
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95th percentile on the average exposure. That is, there is approximately a 95% probability that
the true average exposure is less than this 95th percentile value.
If there are parameters that have important variability and uncertainty components, then a
one-stage simulation may be inadequate. For example, failure to distinguish between uncertainty
and variability can lead to the overstatement of variability in the population. Cohen et al. (1996)
provides a simple example to illustrate this point. In this example, it is supposed that risk
attributable to ingestion of a waterborne carcinogen is equal to the product of the chemical’s
cancer slope factor (CSF) and the water intake rates (IRW). The value of IRW varies from
individual to individual, but is assumed to be known precisely. The CSF value, on the other
hand, is assumed to be the same for all individuals, but its true value is not well-known. A
simulation that fails to distinguish between the variability in IRW values and the uncertainty of
the CSF value would select a random value from each, and multiply these values together to
generate an estimate of risk. However, the distribution generated by repeating this procedure
many times is “wider” than the distribution produced by selecting any one of the possible CSF
values, holding it constant, and multiplying it by ingestion rate values drawn from the IRW
distribution. Figure 1a in Cohen et al. (1996) illustrates several possible distributions. One such
distribution is the “true” distribution (although, it is not known which is true). Moreover, any
one of these distributions is narrower than the distribution generated by a one-stage simulation.
“Two-stage” simulation, which is described in detail in Cohen et al. (1996), properly
addresses uncertainty and variability in cases where both are important. The two-stage
simulation has two iterative loops, referred to as the “inner loop” and the “outer loop.” The inner
loop is, effectively, a one-stage simulation that is restricted to drawing values from probability
distributions representing variability. The result generated by the inner loop is a single
distribution of risks representing the range of risks predicted for a population given a single set
of uncertain parameter values (e.g., the fixed value for the geometric mean and geometric
standard deviation of the soil ingestion rate for children). After execution of the inner loop, the
outer loop selects a new set of uncertain parameter values from the appropriate distributions, and
the inner loop is executed again. This process is repeated, yielding a large number of population
risk distributions, each (in general) corresponding to a different set of uncertain parameter
values. Alternatively, the differences between the variability distributions generated by each
iteration of the outer loop can be viewed as the influence of uncertainty on the estimated
distribution of risks in the population.
At this time, we are unaware of software that implements two-stage simulations without
specialized programming5. Moreover, execution of a two-stage simulation can be
computationally intensive since the total number of iterations is equal to the product of the
number of iterations per execution of the inner loop (typically on the order of 1,000 to 10,000)
and the number of executions of the outer loop (typically on the order of 1,000). Hence, the total
number of iterations can range from 1,000,000 to 10,000,000.
The large amount of information produced by a two-stage simulation presents a challenge
to the interpretation of the results. We recommend that after each iteration of the outer loop,
critical sample statistics be saved, along with the uncertain parameter values used for that inner
5 Cohen et al. (1996) describe the implementation of a two-stage simulation for a Superfund risk assessment. The simulation was implemented
using the SAS statistical programming language (SAS, 199?).
I - 5
loop simulation. For example, after one execution of the inner loop, uncertain parameter values
saved might include the geometric mean and geometric standard deviation of the soil ingestion
distribution, while sample statistics for the calculated value that are recorded might include the
population average risk, the population median risk, and the population 95th percentile risk.
Table I-1 illustrates the saved information for each execution of the outer loop.
Table I-1: Illustrative Results From a Two-Stage Simulation
Outer
Loop
Iteration
Uncertain Parameter Values:
Subscript i,j refers to the value of the ith
parameter for the jth
simulation
Simulation Results 1 U1,1 U2,1 U3,1 U4,1 Average1 Median1 95th Pctl1
2 U1,2 U2,2 U3,2 U4,2 Average2 Median1 95th Pctl1
3 U1,2 U2,2 U3,2 U4,2 Average3 Median1 95th Pctl1
...
1,000 U1,1000 U2,1000 U3,1000 U4,1000 Average1000 Median1000 95th Pctl1000
Note that each result column characterizes a distribution for the corresponding statistic.
By sorting a column of values, confidence intervals can be quantified. For example, if the
column of averages are sorted, the 90 percent confidence interval for the average risk has a lower
bound equal to the 50th value (out of 1,000 values), and an upper bound equal to the 950th value.
It should also be noted that the distribution of values for each of the uncertain parameters will
closely resemble the assumed distributions for these parameters.
The information in Table I-1 can also be used to conduct a sensitivity analysis. As
outlined in Cohen et al. (1996), the influence of each uncertain quantity on any of the results can
be estimated by regressing the calculated value of interest against all of the uncertain parameter
values. Uncertain parameters that strongly influence that calculated value will have a large
incremental R2. Reducing the uncertainty associated with influential parameters will have the
greatest impact on reducing the range of plausible calculated values generated by the simulation.
I .3 Guidelines for the Development of Input Distributions for Key Parameters
This subsection provides guidance on the development of distributions reflecting both
uncertainty and variability (when appropriate) for parameters that appear in the equations
outlined in Appendix H. The parameters discussed include:
Subsection I.3.1: Ingestion rate for water (IRW)
Subsection I.3.2: Ingestion rate for soil (IRS)
Subsection I.3.3: The inhalation rate for air (IRA)
Subsection I.3.4: The soil-to-skin adherence factor (AF)
Subsection I.3.5: Exposure time for bathing (ETshower)
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Subsection I.3.6: Exposure frequency
Subsection I.3.7: Exposure duration
Subsection I.3.8: Body weight
Subsection I.3.9: Body surface area
Subsection I.3.10: Fraction of ingested soil from contaminated site
Subsection I.3.11: Averaging Time
Subsection I.3.12: Contaminant Concentration
Distributions for each of these parameters are discussed in turn.
I.3.1 Water Ingestion Rate (IRW)
Roseberry and Burmaster (1992) fit lognormal distributions to both total water intake and
tap water intake data, for several age groups. For each age group, the authors report that the data
closely follow a lognormal distribution. The summary statistics for these best-fit lognormal
distributions are shown in Table I-2. These distributions are appropriate for describing variability
in water intake. The summary statistics are based on large samples, so the uncertainty in these
quantities should be small compared to the variability. Unless there is reason to believe that
water consumption for a particular population of interest deviates substantially from national
norms, we recommend use of these distributions.
Table I-2: Distribution Statistics: Total Water Intake
Age group
TotalWater Intake
(ml/day)
TapWater Intake
(ml/day)
(years) GM GSD GM GSD
0-1 1,074 1.34 267 1.85
1-11 1,316 1.40 620 1.65
11-20 1,790 1.41 786 1.71
20-65 1,926 1.49 1,122 1.63
> 65 1,965 1.43 1,198 1.61
all 1,785 1.50 963 1.70
Source: Calculated from values in Table I of Roseberry and Burmaster (1992).
I.3.2 Soil Ingestion Rate (IRS)
We characterize the IRS for children and adults separately. USEPA recommends a mean
soil ingestion rate of 100 mg/day for children (USEPA Exposure Factors Handbook 1997. A
typical upper bound value for soil ingestion by children is 200 mg/day. If we assume that this
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upper bound value represents the 95th
percentile, we can fit a lognormal distribution using these
two data points. This yields a distribution with a GM of 88.4 mg/day, and a GSD of 1.64.
USEPA recommends a mean soil ingestion value of 50 mg/day for adults, suggesting that the
adult ingestion rate is approximately one half that of children (USEPA 1997). Based on this
guidance, we recommend that the distribution used for children also be used for adults, but with
a geometric mean that is half of the geometric mean assumed for children. Thus for adults we
obtain a distribution with a GM of 44.2 and a GSD of 1.64.
I.3.3 Inhalation Rate (IRA)
Finley et al. (1994) present percentiles for the distribution of inhalation rates by age;
Table I-6 lists these values. Since derivation of these values are based on assumptions regarding
long term average metabolic rates, they represent average inhalation rates over extended periods.
For each age group the data closely follow a lognormal distribution. The parameters of the best-
fit lognormal distributions are shown in Table I-3.
The text in Section 3.3 of Finley et al. (1994) further describes the derivation of the
percentile values listed in Table I-4. Finley et al. provide no indication that these statistics are
particularly uncertain. However, risk assessors must keep in mind that while these long term
average values may be valid for the population in general, upper end values may be most
appropriate for particularly active subpopulations. Moreover, breathing rates vary substantially
for each individual over the course of a day. While sleeping, inhalation rates are particularly
low. On the other hand, individuals with physically intense occupations will have relatively high
inhalation rates during working hours.
Table I-3: Distribution Percentiles: Inhalation Rate by Age (m3/day)
5% 10% 25% 50% 75% 90% 95% 99%
Age < 3 3.3 3.6 4.1 4.7 5.5 6.2 6.7 7.8
Age 3-10 6.1 6.5 7.3 8.4 9.7 10.9 11.8 13.8
Age 10-18 9.1 9.8 11.2 13.1 15.3 17.7 19.3 22.5
Age 18-30 10.5 11.3 12.8 14.8 17.1 19.5 21.0 24.6
Age 30-60 8.4 9.1 10.2 11.8 13.6 15.4 16.7 19.2
Age > 60 8.5 9.2 10.4 11.9 13.7 15.6 16.7 19.6
Source: Table V in Finley et al. (1994)
Table I-4: Distribution Statistics: Inhalation Rate by Age (m3/day)
GM GSD
Age < 3 4.7 1.2
Age 3-10 8.4 1.2
Age 10-18 13.2 1.3
Age 18-30 14.8 1.2
Age 30-60 11.8 1.2
Age > 60 12.0 1.2
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I.3.4 Soil to Skin Adherence Factor
Finley et al. (1994) present percentiles for the distribution of soil-to-skin adherence
factors, shown in Table I-5. The authors note that values reported in the literature do not vary
significantly by age, so is not necessary to develop age-specific distributions for the adherence
factor. They also report that “soil type, particle size, and indoor vs. outdoor exposure have
minimal influence on soil adherence and therefore do not require consideration in development
of a standard distribution.” As a result, a single distribution is sufficient for the adherence factor.
The data shown in Table I-5 are well characterized by a lognormal distribution with a
geometric mean of 0.5 mg soil per cm2 skin and a geometric standard deviation of 1.9. We
recommend that this distribution be used to characterize uncertainty in the adherence factor, as
Finley et al. (1994) state that it “is believed to predominantly reflect measurement uncertainty.”
Table I-5: Distribution Percentile: Soil to Skin Adherence Factor
Percentile Value (mg soil/cm2 skin)
0.05 0.014
0.1 0.03
0.25 0.05
0.5 0.25
0.75 0.6
0.9 1.2
0.95 1.7
Source: Table IX in Finley et al. (1994).
USEPA’S Exposure Factors Handbook (USEPA), 1997) recommends a slightly different
approach for estimating soil adherence to skin, using data from a study by Kissel et al, (1996).
The study reported soil loading on exposed skin surfaces for different activities. The analyst
may use the soil loading value for the activity which best approximates the exposure scenario.
(See the USEPA) Exposure Factors Handbook.) USEPA notes that insufficient data are
available to develop a distribution or a probability function for soil loading.
I.3.5 Exposure Time for Bathing
USEPA’s Exposure Factors Handbook (USEPA, 1997) provides a frequency distribution
for average shower duration (Table 14-18). The table reports a shower duration of 7 minutes at
the 53rd
percentile, and 15 minutes at the 96th
percentile. If we fit a lognormal distribution to
these data, we obtain a GM of 6.8 minutes and a GSD of 1.6. Since the lognormal places
positive weight on shower duration values that are implausible (i.e., values very close to zero,
and values that are arbitrarily large), it is recommended that the distribution be truncated at its
2.5 percentile value of 2.7 minutes, and its 97.5 percentile value of 17 minutes.
I - 9
I.3.6 Exposure Frequency
The distribution for this parameter depends on factors specific to the exposure scenario.
In general, the exposure frequency for a residential exposure scenario can be assumed to be
approximately 350 days per year (which reflects an assumption that individuals spend two weeks
per year away from home – e.g., on vacation). The exposure frequency for occupational
scenarios can be assumed to be approximately 250 days per year (which reflects the assumption
that individuals work 5 days per week for 50 weeks per year).
It is suspected that for these standard scenarios, this parameter is not highly uncertain.
On the other hand, for special exposure scenarios (e.g., a trespasser visiting a site that is off-
limits to the public), the exposure frequency may be highly uncertain. Very often, no empirical
data for this parameter will even be available. In these cases, the risk assessor should take into
account meteorological conditions that would limit the frequency of exposure (e.g., it is unlikely
that trespassers would visit an outdoor site on days when it rains; when the temperature is below
freezing, access to contaminated soil may be limited).
I.3.7 Exposure Duration
Typically, exposure duration is assumed to reflect the amount of time an individual lives
at a single location. Cohen et al. (1996) describe the derivation of lognormal distributions
describing this parameter for both rural and urban households using data published by Israeli et
al. (1992). In both cases, the data are well described by the lognormal. For urban households,
the geometric mean is 5.32 years, with a geometric standard deviation of 6.48. For rural
households, the geometric mean is 6.48 years, with a geometric standard deviation of 3.20.
For occupational exposures, exposure duration is assumed to reflect occupational tenure.
Shaw and Burmaster (1996) detail values for the amount of time individuals spend between job
changes. This information is presented for men and women separately by industry type.
I.3.8 Body Weight
USEPA (1997) reports that children’s body weights are well described by lognormal
distributions. Table I-6 lists these parameters, which are provided for each year of age through
age 20.
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Table I-6: Distribution Parameters: Children’s Body Weight (kg)
Age Females Males
(years) GM GSD GM GSD
0.5-1 8.67 1.16 9.30 1.14
1-2 10.80 1.14 11.70 1.13
2-3 12.94 1.12 13.46 1.13
3-4 14.73 1.15 15.64 1.12
4-5 16.95 1.14 17.64 1.14
5-6 19.69 1.18 19.89 1.15
6-7 22.20 1.19 22.87 1.16
7-8 24.29 1.19 24.78 1.16
8-9 27.39 1.17 27.94 1.20
9-10 31.82 1.24 30.88 1.18
10-11 35.52 1.22 36.23 1.22
11-12 40.85 1.25 40.04 1.29
12-13 45.60 1.24 43.82 1.25
13-14 50.40 1.24 48.42 1.24
14-15 54.05 1.21 55.70 1.20
15-16 54.60 1.17 59.74 1.17
16-17 57.97 1.18 66.69 1.18
17-18 59.15 1.18 66.02 1.18
18-19 58.56 1.16 70.11 1.17
19-20 60.34 1.16 70.81 1.17
Source: Parameters calculated from log parameters given in USEPA, 1996a..
Brainard and Burmaster (1992) report that adult body weights are also lognormally
distributed. Body weights for women follow a lognormal distribution with a GM of 143 pounds
and a geometric standard deviation of 1.2. Body weights for men are also lognormally
distributed with GM = 169 pounds and GSD = 1.2.
Because body weights can be measured very accurately and the distribution of body
weights in the population has been extensively studied and well characterized, the body weight
distributions described here represent variability rather than uncertainty. That is, the magnitude
of any inter-individual variability far exceeds the magnitude of the uncertainty in these
distributions.
We recommend that it be assumed that body weights are correlated over time. In other
words, it should be assumed that individuals who are relatively heavy at one age are also
relatively heavy at later ages, while those who are light tend to remain light. Perfect correlation
of body weights over time can be modeled by specifying that an individual’s weight percentile
does not change. For example, an individual whose weight places him or her in the 30th
percentile at age 10 is assumed to have a body weight placing him or her in the 30th percentile
for weight at any other age. Perfect correlation can be implemented by randomly selecting the
percentile for a simulated individual (i.e., a value between 0% and 100%), and then selecting the
corresponding value of the body weight distribution for each age listed in Table I-6.
I - 11
Cancer toxicity factors (slope factors and unit risks) are derived assuming a body weight
of 70 kg. These toxicity factors must be adjusted, as discussed in USEPA 1996a, if body weights
other than 70 kg are assumed. Ordinarily, this assumption will be left unchanged, making
adjustment unnecessary. The derivation of noncancer toxicity factors (reference doses [RFDs]
and reference concentrations [RFCs]) does not depend on body weight, so no adjustment is
necessary for these factors.
I.3.9 Body Surface Area
Finley et al. (1994) note that studies of total body surface area have found that surface
area and body weight are strongly associated. Specifically, SA is equal to the product of BW
and a ratio (R). The ratio R is lognormally distributed for children under age 2 years with an
arithmetic mean of 641 cm2 / kg and a standard deviation of 114 cm
2 / kg. These parameters
correspond to a geometric mean of 631 cm2 / kg, and a GSD of 1.19. For individual over the age
of 2 years, R follows a normal distribution. For individuals between 2 and 18 years, the mean
and standard deviation of this normal distribution is 423 cm2 / kg and 76 cm
2 / kg, respectively;
for individuals over the age of 18, the mean and standard deviation are 284 cm2 / kg, and 28 cm
2
/ kg, respectively.
Hence, once a body weight is determined probabilistically, as described in Subsection
I.3.8, a value of R can be chosen randomly from the appropriate distribution described in the
preceding paragraph. Total body surface area can then be computed by multiplying BW and R.
If the surface area of some portion of the human body must be determined, it is recommended
that the randomly generated total body surface area be multiplied by the appropriate mean
percentage listed in Table I-7.
Table I-7: Average Fraction of Total Body Surface Area Corresponding to Head, Arms,
Hands, Legs, and Feet
Body Part – Percent of Total Body Surface Area
Age (years) Head Arms Hands Legs Feet
< 1 18.2 13.7 5.3 20.6 6.54
1-2 16.5 113.0 5.68 23.1 6.27
3-4 13.6 14.4 6.07 26.8 7.21
4-5 13.8 14.0 5.70 27.8 7.29
9-10 12.0 12.3 5.30 28.7 7.58
Men > 18 7.8 14.1 5.2 31.2 7.0
Women> 18 7.1 14.0 5.1 32.4 6.5
Source: Table IV in Finley et al. (1994). Note that Finley also provides minimum and
maximum values for these parameters. However, it is unlikely that variability in the values of
these parameters across members of the population would yields substantial differences in
exposure or risk.
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I.3.10 Fraction of Ingested Soil from a Contaminated Site
This parameter is site-specific and population-specific. Determining the range of
plausible values for the population will depend on collection of either empirical data or on the
adoption of reasonable assumptions. For example, if the risk assessment aims to quantify risks
associated with soil ingestion at a non-residential site, it may be reasonable to assume that
individuals spend fewer than half their waking hours at the site (on days when they visit the site
at all), and hence that FI should be no larger than 0.5.
I.3.11 Averaging Time
It is not appropriate to use a distribution for the averaging time in either the cancer or
noncancer risk equations. A 70 year lifetime should be used as the averaging time for cancer
risks because the derivation of the cancer toxicity factors (slope factors or unit risks) reflects the
assumption of a 70 year lifetime (USEPA, 1997).
The derivation of chronic noncancer risk parameters reflects the assumption that
exposure is averaged over a “chronic period,” which is defined to be 7 years. Note that for
exposures lasting more than 7 years, the noncancer risk is calculated using that 7 “window”
during which average exposure is greatest. If the maximum exposure (on a mg/kg-day basis) is
constant for 7 years or more, then noncancer risk can be calculated by comparing the RfD to the
constant level of exposure during this period. In summary, the averaging time for noncancer risk
assessment is always 7 years. However, the 7 year period over which exposure is averaged
depends on the exposure pattern over time. Specifically,
If exposure lasts for less than 7 years, the exposure compared to the RfD is
total exposure (mg/kg) divided by 2,555 days (7 years 365 days/year);
If exposure exceeds 7 years, the exposure compared to the RfD is the
maximum total exposure (mg/kg) over any 7-year period divided by 2,555
days;
If exposure exceeds 7 years and is constant when expressed as mg/kg-day,
then this constant level of exposure is compared directly to the RfD.
The ratio of the appropriately calculated exposure, as described above) to the RfD is the
hazard index.
I.3.12 The Concentration Term
As noted in Section H.1, the concentration term corresponds to a contaminant’s average
concentration at a “site.” Here, it is assumed that the site has been divided into exposure units,
which are defined by USEPA (1996b) to be an area within which the probability of exposure to
all locations is equal. It is also assumed that individuals come into contact with an exposure unit
a large number of times. Hence, the average contaminant concentration to which they are
exposed is equal to the average contaminant concentration within the exposure unit.
I - 13
The advantage of this approach is that it simplifies analysis of variability. Specifically,
variability is addressed by conducting a separate risk assessment for each exposure unit. The
“drawback” of the approach is that it potentially requires division of a site into exposure units
satisfying the definition specified above. For example, if a site is divided by a large stream, it
may make sense to define the areas of the site on the two sides of the river as distinct exposure
units. It should be noted that in a one-dimensional analysis of variability of exposure, the
concentration term is the average concentration in an exposure area. The average concentration
should be treated as a constant, not a variable.
It must also be kept in mind that uncertainty in the value of the average exposure unit
concentration may have to be addressed.. Typically, this lack of precision reflects the finite
number of observations used to quantify contaminant concentrations. Characterizing the
distribution of plausible values for the average within the exposure unit depends on assumptions
regarding the distribution of concentration values within the exposure unit.
USEPA guidance (1992) states that if the concentration values follow a normal
distribution, then the mean follows a Student’s “t” distribution. The value of a percentile () for
the distribution describing the set of plausible values for the mean is described as
x t s nn 1 1 , ( / )
where n is the sample size, x is the sample mean, s is the sample standard deviation, and t1-,n-1 is
the 1- percentile of the student t distribution with n-1 degrees of freedom.
If the contaminant concentration is assumed to be lognormally distributed (which is often
the case), then USEPA recommends assuming that plausible values for the mean fall within a
range between a lower and upper percentile bound defined by the expression,
ex
s sH
n
2
2 1
where x is the sample mean of the log of the observations, and s is the sample standard deviation
of the log of the observations. The lower bound value for this range is determined by using a
lower-end fractile value for H (e.g., the 5% value), while the upper bound value for this range
makes use of an upper-end fractile value for H (e.g., the 95% value). A randomly selected value
for the mean can be generated as follows. First, select a percentile from the uniform distribution
between 0 and 1. Then identify the corresponding H value. Finally, plug this H value into the
preceding equation. Cohen et al. (1996) describe the development of a distribution for plausible
values of the mean contaminant concentration at a Superfund site using the preceding equation.
There are several techniques to determine whether concentration values are normally
distributed (in which case the t statistic should be used to characterize plausible values of the
mean), or lognormally distributed (in which case the H statistic should be used to calculate the
distribution characterizing plausible values of the mean). First, there are tests of normality built
into various statistics packages. For example, the W-test (Gilbert, 1987) indicates whether the
hypothesis of normality can be rejected. Applying this test to the untransformed data indicates
whether the data can be considered to be normally distributed. Applying this test to the log-
transformed values of the data indicates whether the data can be considered to be lognormally
distributed. Specifically, failure to reject the hypothesis of normality when applying the test to
log-transformed data values indicates the data are lognormal.
I - 14
A complication that may be encountered is the case in which the hypothesis of normality
is rejected both when the test is applied to the untransformed data and when it is applied to the
log-transformed data. In this case, graphical methods may provide a better idea of which (if
either) distribution best describes the observed concentrations. One commonly used method is
the probability plot method described by Gilbert (1987).
Finally, maximum likelihood techniques can be used to characterize the set of
distributions that may plausibly describe the data. The collection of mean statistics
corresponding to each of these distributions represents the set of plausible mean values
consistent with the data. The following discussion briefly outlines the use of this technique when
the data are assumed to be lognormally distributed.
Suppose we have observations denoted x1, x2, ... xN. The log of these concentrations are
denoted y1, y2, ... , yN. We start by computing the maximum likelihood estimates for the mean
(denoted ) and standard deviation (denoted ) of the log-transformed data:
1
1Nyi
i
N
and
1 2
1Nyi
i
N
( )
Next, we define the log likelihood function for any set of estimates for the mean and
standard deviation of the log transformed data set (y1, y2, ... , yN). Denote the alternative
estimates for the mean and standard deviation as j and k. Then the log-likelihood function, L
( j, k) is
L f xj k i
i
N
j k( , ) ln[ ( , , )]
1
where f(xi, j, k) is the density function of the lognormal with parameters ln(geometric mean) =
j and ln(geometric standard deviation) = k evaluated at data point xi. The density function
f(xi,,) is denoted
f xx
ei j k
i
xi
( , , )
ln
1
2
1
2
2
Note that L( j, k) can now be expressed as
L yy
j k
i
N
k i
i j
k
( , ) ln( ) ln( )
21
21
2
The 95% confidence region is the set of all j and k that satisfy the relationship
2 2 0 95 2
2 L L j k( , ) ( , ) . ,
I - 15
where 0 95 2
2
. , denotes the 95th percentile of the chi-square distribution with 2 degrees of
freedom.
Each pair of parameters (,) in this region corresponds to a lognormal distribution, each
of which has a corresponding mean. A Monte Carlo simulation can randomly select average
contaminant concentration values by randomly selecting a parameter pair from this region and
then calculating the arithmetic mean that corresponds to that pair.
I.4 Calculation of Cleanup Levels Using Probabilistic Techniques
Acceptable average soil contaminant levels can be derived from a “backwards” solution
to the appropriate risk equation. In the case of cancer risk assessment, the original equation,
which quantifies risk as a function of exposure terms (e.g., exposure frequency, ingestion, rate,
etc.) is rearranged so that the concentration term is expressed as a function of the other exposure
terms and the maximum acceptable risk level (e.g., 10-5
). In the case of non-cancer risk
assessment, the original equation quantifying daily dose is rearranged so that concentration is
expressed as a function of the other exposure terms and the maximum acceptable dose – i.e., the
RfD.
Although Burmaster et al, (1998) and Ferson (1996) have pointed out the difficulty of
performing back-calculations for cleanup levels when probabilistic risk assessment is used, back-
calculation can be used under certain limiting conditions, specifically, when the target risk is set
by a single value (Burmaster and Thompson, 1995). An example of a single value target risk for
cancer is that 95% of the population must have a risk below 10-6
.
The probabilistic calculation is performed doing back-calculation with the risk parameter
specified as the single value representing the target (e.g., 10-6
). This simulation yields a
distribution of soil contaminant concentration values. To ensure that, for example, the 90th
percentile risk does not exceed the maximum acceptable risk (in the case of carcinogens) or that
the 90th percentile dose does not exceed the RfD (in the case of noncarcinogens), the 10th
percentile of the soil contaminant concentration distribution generated by the simulation is
selected as the maximum acceptable average concentration. In general, selection of the p fractile
of the soil contaminant concentration distribution ensures that either the (1-p) fractile risk does
not exceed the maximum acceptable risk or that the (1-p) fractile dose does not exceed the RfD.
Calculation of a site-specific “pickup level” involves further statistical analysis that
makes use of the maximum acceptable average contaminant concentration, as described in the
preceding paragraph, and information regarding the site-specific distribution of contaminant
concentrations. The so-called “cleanup remediation goal” or “CRG” approach that identifies the
pickup level requires use of specialized software. The methodology is outlined in Bowers et al.
(1996). A revised version of this methodology will be available later in 1997. Removal of all
soil with contaminant concentrations exceeding the pickup level ensures that the site-wide
average concentration is less than the acceptable average concentration with some specified level
of confidence.
I - 16
I.5 References
Bowers, T.S., N.S. Shifrin, and B.L. Murphy. 1996. Statistical Approach To
Meeting Soil Cleanup Goals. Environ. Sci. Technol. 30 (5): 1437-1444.
Brainard, J. and Burmaster, DE. 1992. Bivariate Distributions For Height And
Weight Of Men And Women In The United States. Risk Anal. 12 (2): 267-275.
Burmaster, D.E., Lloyd, K.J., and Thompson, K.M. 1995. The Need For New
Methods To Backcalculate Soil Cleanup Targets In Interval And Probabilistic
Cancer Risk Assessments. Hum. Ecol. Risk Assess. 1,89-100.
Burmaster, D.E., Lloyd, K.J., and Thompson, K.M. 1995. Backcalculating
Cleanup Targets In Probabilistic Risk Assessments When The Acceptability Of
Cancer Risk Is Defined Under Different Risk Management Policies. Hum. Ecol.
Risk Assess. 1, 101-120.
Calabrese, E.J., E.S. Stanek, and C.E. Gilbert. 1991. A Preliminary Decision
Framework For Deriving Soil Ingestion Rates. In: Calabrese, E.J, and P.T.
Kostecki, eds. Petroleum Contaminated Soils 2(29). Lewis, Chelsea, MI.
Cohen, J.T., Lampson, M.A., and Bowers, T.S. 1996. The Use Of Two-Stage
Monte Carlo Simulation Techniques To Characterize Variability And Uncertainty
In Risk Analysis. Human and Ecological Risk Assessment. 2(4): 939-971.
Ferson, S. 1996. What Monte Carlo Methods Cannot Do. Hum. Ecol. Risk
Assess. 2, 990-1007.
Finley, B., Proctor, D., Scott, P., Harrington, N., Paustenbach, D., and Price, P.
1994. Recommended Distributions For Exposure Factors Frequently Used In
Health Risk Assessments. Risk Anal. 14(4): 533-553.
Gilbert, RO. 1987. Statistical Methods for Environmental Pollution Monitoring.
Van Nostrand Reinhold (New York, NY).
Kissel et al., 1996. Kissel, J., K. Richter, R. Fenske. Field Measurements Of
Dermal Soil Loading Attributable To Various Activities: Implication For
Exposure Assessment. Risk Anal. 16(1):116-125.
Israeli, M., C.B. Nelson. 1992. Distribution And Expected Time Of Residence
For US Households. Risk Anal. 12 (1): 65-72.
Roseberry, A.M., and Burmaster, DE. 1992. Lognormal Distributions For Water
Intake By Children And Adults. Risk Anal. 12(1): 99-104.
Shaw, C.D., and D.E. Burmaster. 1996. Distributions Of Job Tenure For U.S.
Workers In Selected Industries And Occupations. Human and Ecological Risk
Assessment. 2(4): 798-819.
I - 17
US Environmental Protection Agency (USEPA). 1989. Risk Assessment
Guidance for Superfund. Volume II: Environmental Evaluation Manual. Office
of Emergency and Remedial Response (Washington, DC). EPA-540/1-89-001.
March.
U.S. Environmental Protection Agency (USEPA). 1992. Office of Solid Waste
and Emergency Response (Washington, DC). Supplemental Guidance to RAGS:
Calculating the Concentration Term. OSWER Publication 9285.7-081;NTIS
PB92-963373. 8p. May 1992.
US Environmental Protection Agency (USEPA). 1996a. Summary Report for the
Workshop on Monte Carlo Analysis. Office of Research and Development
(Washington, D.C.). EPA/630/R-96/010. September.
US Environmental Protection Agency (USEPA). 1996b. Soil Screening
Guidance: Technical Background Document. Office of Solid Waste and
Emergency Response (Washington, DC). May. EPA/540/R-95/128. PB96-
963502.
US Environmental Protection Agency (USEPA). 1997. Office of Health and
Environmental Assessment, Exposure Assessment Group. Exposure Factors
Handbook – Volumes I, II and III. EPA/600/P-97/002FA,B,C.
J - 1
APPENDIX J: OFFICE OF WATER RESOURCES IN-STREAM MONITORING
PROCEDURES TO DETERMINE IMPACT ON THE SURFACE WATER FROM NON-
POINT SOURCE SITE REMEDIATION PROJECTS
BACKGROUND:
The Water Quality Standards Rule, 46CSR1, Section 5, allows the Chief of the Office of
Water Resources to determine, on a case-by-case basis, definable geometric limits for mixing
zones for a discharge or a pollutant or pollutants within a discharge, upon the request of a permit
applicant or permittee. These rules are tailored for point source discharges in order to further
protect water quality after the imposition of technology-based treatment standards, best available
treatment, on the point source discharge. Site remediation projects which constitute non-point
sources are not required to obtain permits. Therefore, in order to protect water quality and
achieve compliance with the rules, the Chief of the Office of Water Resources will require
implementation of the following in-stream monitoring procedures to be used to determine the
impact on the receiving stream, in conjunction with site remediation projects.
In-Stream Monitoring Procedures
All samples will be collected for the specific pollutants of concern and using accepted
QA/QC procedures. Surface water samples will be collected as follows:
Upstream Sampling Location(s)
A. 25’ from property line
B. Vertical mid-point of the water column
C. A sampling location for each 50’ of river width, spaced equally
Downstream Sampling Location(s)
A. 25’ from property line
B. Vertical mid-point of the water column
C. A sampling location for each 25’ of river width, spaced equally, up to 100’ of river
width
Additional Sampling Location(s)
An additional sampling will be performed if the property (shoreline) exceeds 200’. For
each additional 200’ of the property, sampling locations will be as follows:
A. A sampling point for each 25’ of river width, spaced equally, up to 100’ of river
width.
B. Vertical mid-point of the water column.
C. Spaced equally between upstream and downstream sampling locations.
Please contact the West Virginia Secretary of State’s Office at (304) 558-6000 or
http://www.state.wv.us/sos/adlaw/alreqser.htm for copy of:
TITLE 60
LEGISLATIVE RULE
DIVISION OF ENVIRONMENTAL PROTECTION
DIRECTOR’S OFFICE
SERIES 3
VOLUNTARY REMEDIATION AND REDEVELOPMENT RULE
March 13, 2001
The changes between Version 2.0 and Version 2.1 are:
APPENDIX C-2: CHECKLIST TO DETERMINE THE APPLICABLE ECOLOGICAL
STANDARD